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Estimation of left ventricular activation sequence in patients with heart failure using two-dimensional speckle tracking echocardiography

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INTERNATIONAL JOURNAL OF CARDIOVASCULAR IMAGING 2023年第7期39卷 1251-1262页

作者： Hara, Hideyuki Igarashi, Tazuru Kaida, Toyoji Murakami, Masami Ito, Hiroshi Niwano, Shinichi Ako, Junya Numazu City Hosp Div Cardiol Aza Harunoki 550 Numazu Shizuoka 4100302 Japan Kitasato Univ Dept Cardiovasc Med Sch Med Sagamihara Japan

Evaluation of longitudinal strain (LS) from two-dimensional echocardiography is useful for global and regional left ventricular (LV) dysfunction assessment. We determined whether the LS reflects contraction process in patients with asynchronous LV activation. We studied 144 patients with an ejection fraction <= 35%, who had left bundle branch block (LBBB, n = 42), right ventricular apical (RVA) pacing (n = 34), LV basal- or mid-lateral pacing (n = 23), and no conduction block (Narrow-QRS, n = 45). LS distribution maps were constructed using 3 standard apical views. The times from the QRS onset-to-early systolic positive peak (Q-EPpeak) and late systolic negative peak (Q-LNpeak) were measured to determine the beginning and end of contractions in each segment. Negative strain in LBBB initially appeared in the septum and basal-lateral contracted late. In RVA and LV pacing, the contracted area enlarged centrifugally from the pacing site. Narrow-QRS showed few regional differences in strain during the systolic period. The Q-EPpeak and Q-LNpeak exhibited similar sequences characterized by septum to basal-lateral via the apical regions in LBBB, apical to basal regions in RVA pacing, and lateral to a relatively large delayed contracted area between the apical- and basal-septum in LV pacing. Differences in Q-LNpeaks between the apical and basal segments in delayed contracted wall were 107 +/- 30 ms in LBBB, 133 +/- 46 ms in RVA pacing, and 37 +/- 20 ms in LV pacing (p < 0.05, between QRS groups). Specific LV contraction processes were demonstrated by evaluating the LS distribution and time-to-peak strain. These evaluations may have potential to estimate the activation sequence in patients with asynchronous LV activation.

关键词： Longitudinal strain Time-to-peak strain Bull's eye map Left bundle branch block Right ventricular pacing activation sequence

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Mitigating Cd(II) contamination form aqueous solution by phosphate-activated sludge biochar: Role of effect of activation sequence

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JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING 2024年第6期12卷

作者： Xiao, Jiang Mo, Guanhai Zhou, Shukui Univ South China Sch Civil Engn Hengyang 421001 Peoples R China

Phosphate-activation sequence has vital influence on the performance and mechanism of Cd(II) removal by biochar. Hence, the difference activation sequences (pyrolysis-impregnation, impregnation-pyrolysis and copyrolysis) were employed to produce K3PO4 activated sludge biochar to investigate the differences of Cd(II) sorption behavior and mechanism from aqueous solution. Compared to pristine sludge biochar (SBC) and pyrolysis-impregnation activated biochar (SBC-IB), the surface of impregnation-pyrolysis activated sludge biochar (SBC-IS) and co-pyrolysis activated sludge biochar (SBC-CS) exhibited rougher, more porous and higher graphitized. Compared to SBC (66.53 mg/g), SBC-IB (141.89 mg/g) and SBC-IS (175.34 mg/g), SBC-CS (262.39 mg/g) possessed the largest Cd(II) adsorption capacity at 303 K. The sorption mechanism could include complexation, precipitation, Cd(II)-pi interaction and cation exchange. By quantifying the mechanism contribution, pyrolysis-impregnation mainly improved complexation capacity, whereas impregnation-pyrolysis and co-pyrolysis primarily enhanced the contribution of precipitation and ion exchange. This work could provide a comprehensive guide for phosphate-activated biochar.

关键词： Phosphate-activated sludge biochar activation sequence Cadmium ion Adsorption behavior Potential mechanism

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A left bundle branch block activation sequence and ventricular pacing influence voltage amplitudes: an in vivo and in silico study

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EUROPACE 2018年第Sup3期20卷 77-86页

作者： Uyen Chau Nguyen Potse, Mark Vernooy, Kevin Mafi-Rad, Masih Heijman, Jordi Caputo, Maria Luce Conte, Giulio Regoli, Francois Krause, Rolf Moccetti, Tiziano Auricchio, Angelo Prinzen, Frits W. Maffessanti, Francesco Maastricht Univ Med Ctr Cardiovasc Res Inst Maastricht CARIM Dept Physiol POB 616 NL-6200 MD Maastricht Netherlands MUMC Dept Cardiol CARIM Maastricht Netherlands Inria Bordeaux Sud Ouest CARMEN Res Team F-33400 Talence France Univ Bordeaux IMB UMR 5251 F-33400 Talence France Fdn Bordeaux Univ IHU Liryc Electrophysiol & Heart Modeling Inst F-33600 Bordeaux France Radboud Univ Nijmegen Dept Cardiol Med Ctr Nijmegen Netherlands Fdn Cardioctr Ticino Dept Cardiol Lugano Switzerland Univ Svizzera Italiana CCMC Inst Computat Sci Lugano Switzerland

Aims The aim of this study was to investigate the influence of the activation sequence on voltage amplitudes by evaluating regional voltage differences during a left bundle branch block (LBBB) activation sequence vs. a normal synchronous activation sequence and by evaluating pacing-induced voltage differences. Methods and results Twenty-one patients and three computer models without scar were studied. Regional voltage amplitudes were evaluated in nine LBBB patients who underwent endocardial electro-anatomic mapping (EAM). Pacing-induced voltage differences were evaluated in 12 patients who underwent epicardial EAM during intrinsic rhythm and right ventricular (RV) pacing. Three computer models customized for LBBB patients were created. Changes in voltage amplitudes after an LBBB (intrinsic), a normal synchronous, an RV pacing, and a left ventricular pacing activation sequence were assessed in the computer models. Unipolar voltage amplitudes in patients were approximately 4.5mV (4.4-4.7 mV, similar to 33%) lower in the septum when compared with other segments. A normal synchronous activation sequence in the computer models normalized voltage amplitudes in the septum. Pacing-induced differences were larger in electrograms with higher voltage amplitudes during intrinsic rhythm and furthermore larger and more variable at the epicardium [mean absolute difference: 3.6-6.2 mV, 40-53% of intrinsic value;interquartile range (IQR) differences: 53-63% of intrinsic value] compared to the endocardium (mean absolute difference: 3.3-3.8 mV, 28-30% of intrinsic value;IQR differences: 37-40% of intrinsic value). Conclusion In patients and computer models without scar, lower septal unipolar voltage amplitudes are exclusively associated with an LBBB activation sequence. Pacing substantially affects voltage amplitudes, particularly at the epicardium.

关键词： Voltage amplitude Intra-cardiac electrogram Heart failure Left bundle branch block activation sequence Computer models Anisotropy

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Human ventricular activation sequence and the simulation of the electrocardiographic QRS complex and its variability in healthy and intraventricular block conditions

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EUROPACE 2016年第suppl 4期18卷 4-15页

作者： Cardone-Noott, Louie Bueno-Orovio, Alfonso Minchole, Ana Zemzemi, Nejib Rodriguez, Blanca Univ Oxford Dept Comp Sci Oxford OX1 3QD England Univ Oxford British Heart Fdn Ctr Res Excellence Oxford OX1 3QD England INRIA Bordeaux Sud Ouest 200 Ave Vieille Tour F-33405 Talence France Fdn Bordeaux Univ IHU Liryc Electrophysiol & Heart Modeling Inst F-33600 Bordeaux France

Aims To investigate how variability in activation sequence and passive conduction properties translates into clinical variability in QRS biomarkers, and gain novel physiological knowledge on the information contained in the human QRS complex. Methods and results Multiscale bidomain simulations using a detailed heart-torso human anatomical model are performed to investigate the impact of activation sequence characteristics on clinical QRS biomarkers. activation sequences are built and validated against experimentally-derived ex vivo and in vivo human activation data. R-peak amplitude exhibits the largest variability in terms of QRS morphology, due to its simultaneous modulation by activation sequence speed, myocardial intracellular and extracellular conductivities, and propagation through the human torso. QRS width, however, is regulated by endocardial activation speed and intracellular myocardial conductivities, whereas QR intervals are only affected by the endocardial activation profile. Variability in the apico-basal location of activation sites on the anterior and posterior left ventricular wall is associated with S-wave progression in limb and precordial leads, respectively, and occasional notched QRS complexes in precordial derivations. Variability in the number of early activation sites successfully reproduces pathological abnormalities of the human conduction system in the QRS complex. Conclusion Variability in activation sequence and passive conduction properties captures and explains a large part of the clinical variability observed in the human QRS complex. Our physiological insights allow for a deeper interpretation of human QRS biomarkers in terms of QRS morphology and location of early endocardial activation sites. This might be used to attain a better patient-specific knowledge of activation sequence from routine body-surface electrocardiograms.

关键词： Electrocardiogram QRS complex activation sequence Variability Computer modelling and simulation

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Allocation and activation of resource constrained shock-exposed components in heterogeneous 1-out-of-n standby system

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RELIABILITY ENGINEERING & SYSTEM SAFETY 2024年 241卷

作者： Levitin, Gregory Xing, Liudong Dai, Yuanshun Southwest Jiaotong Univ Sch Comp & Artificial Intelligence Chengdu Peoples R China NOGA Israel Independent Syst Operator Haifa Israel Univ Massachusetts Dartmouth Dartmouth MA 02747 USA Graph Era Deemed Be Univ Dept Comp Sci & Engn Dehra Dun India

In real-world mission-critical applications like unmanned aerial vehicles (UAVs), the standby sparing design method is typically applied to enhance the mission success probability (MSP), and standby components may reside in different physical positions exposed to diverse random environments/shocks affecting components' failure behaviors. Thus, the position allocation of standby components may affect the MSP greatly. Moreover, the MSP varies for different activation sequences of standby components. This paper makes contributions by formulating and solving the optimal position allocation and activation sequence (PAAS) problem to maximize the MSP of a 1-out-of -n standby system with n non-identical components, characterized by different performance speeds, initial resource (determining the maximum amount of mission work that can be completed by each component), and shock resistance levels. The rate of shocks affecting each component is dependent on the component's position and mode (standby, activation, or operation). We put forward a new numerical algorithm for evaluating the MSP, the probability that the considered standby system can compete a specified amount of work before all the system components stop operation due to failures or resource depletion. We further apply the genetic algorithm to solve the PAAS co-optimization problem. A multi-UAV surveillance system is studied to showcase the proposed standby system model and impacts of several component and shock parameters on the mission reliability and PAAS optimization solutions.

关键词： Standby systems Limited resource Shocks Position allocation activation sequence Unmanned aerial vehicles

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Inspection and maintenance optimization for heterogeneity units in redundant structure with Non-dominated Sorting Genetic Algorithm III

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ISA TRANSACTIONS 2023年 135卷 299-308页

作者： Zhang, Aibo Hao, Songhua Xie, Min Liu, Yiliu Yu, Haoshui City Univ Hong Kong Dept Adv Design & Syst Engn Hong Kong Peoples R China Hong Kong Sci Pk Ctr Intelligent Multidimens Data Anal Hong Kong Peoples R China Sichuan Univ Sch Aeronaut & Astronaut Chengdu Peoples R China Norwegian Univ Sci & Technol Dept Mech & Ind Engn Trondheim Norway Aalborg Univ Dept Chem & Biosci Esbjerg Denmark Aalborg Univ Dept Chem & Biosci Niels Bohrs Vei 8A DK-6700 Esbjerg Denmark

Redundant structure has been widely deployed to improve system reliability, as when one unit fails, the system can continue to function by using another one. Most existing studies rely on the similar assumption that the heterogeneous units are subject to periodic inspections and identical in terms of their aging situations and the numbers of resisted shocks. In practice, it is often adequate to trigger a unit individually in the event of a single shock, which intensifies the degradation of that unit, accordingly, requiring a sooner inspection to ensure its safety. In this study, the stochastic dependency among units is addressed firstly by introducing a novel activation sequence. Secondly, an adaptive system-level inspection policy is proposed by prioritizing the unit with a worse state. Finally, we take advantage of Monte Carlo methods to simulate the whole process and estimate two objectives, referring to the average system unavailability and maintenance cost, in a designed service time. It is found that the two objectives are contradictory through numerical examples. The Non-dominated Sorting Genetic Algorithm III (NSGA-III) algorithm, therefore, has been employed to find the optimal solutions in system unavailability and cost, which provide clues for practitioners in decision-making.(c) 2022 The Author(s). Published by Elsevier Ltd on behalf of ISA. This is an open access article under the CC BY license (http://***/licenses/by/4.0/).

关键词： activation sequence Adaptive inspection Redundant structure 1oo2 configuration Maintenance optimization NSGA-III algorithm

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Inverse estimation of cardiac activation times via gradient-based optimization

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018年第2期34卷 1-1页

作者： Kallhovd, Siri Maleckar, Mary M. Rognes, Marie E. Simula Res Lab POB 134 N-1325 Lysaker Norway Univ Oslo Dept Informat POB 1080 N-0316 Oslo Norway Univ Oslo Dept Math POB 1053 N-0316 Oslo Norway Ctr Cardiol Innovat Sognsvannsveien 9 N-0372 Oslo Norway Ctr Biomed Comp POB 134 N-1325 Lysaker Norway Allen Inst Cell Sci 615 Westlake Ave Seattle WA 98109 USA

Computational modeling may provide a quantitative framework for integrating multiscale data to gain insight into mechanisms of heart disease, identify and test pharmacological and electrical therapy and interventions, and support clinical decisions. Patient-specific computational cardiac models can help guide such procedures, and cardiac inverse modeling is a promising alternative to adequately personalize these models. Indeed, full cardiac inverse modeling is currently becoming computationally feasible;however, fundamental work to assess the feasibility of emerging techniques is still needed. In this study, we use a partial differential equation-constrained optimal control approach to numerically investigate the identifiability of an initial activation sequence from synthetic (partial) observations of the extracellular potential using the bidomain approximation and 2D representations of cardiac tissue. Our results demonstrate that activation times and duration of several stimuli can be recovered even with high levels of noise, that it is sufficient to sample the observations at the electrocardiogram-relevant sampling frequency of 1kHz, and that spatial resolutions that are coarser than the standard in electrophysiological simulations can be used. The optimization of activation times is still effective when synthetic data are generated with a different cell membrane kinetics model than optimized for. The findings thus indicate that the presented approach has potential for finding activation sequences from clinical data modalities, as an extension to existing cardiac imaging approaches.

关键词： activation sequence adjoint bidomain model cardiac electrophysiology PDE-constrained optimization

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Mit :: Lcs :: Tr :: Mit-Lcs-Tr-981

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2016年

Mit :: Lcs :: Tr :: Mit-Lcs-Tr-981 by published by

关键词： activation sequence dispute dispute ring dispute wheel hop hop count mit-lcs-tr-981 node nodes path path assignment paths ranking ranking independence rankings routing routing system routing systems shortest hop stable path system

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Stochastic activation among inspiratory cells in the pre-Botzinger complex of the rat medulla revealed by Ca²⁺ imaging

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NEUROSCIENCE LETTERS 2015年第0期595卷 12-17页

作者： Oke, Yoshihiko Boiroux, Dimitri Miwakeichi, Fumikazu Oku, Yoshitaka Hyogo Coll Med Div Physiome Dept Physiol Nishinomiya Hyogo 6638501 Japan Inst Stat Math Dept Stat Modeling Tachikawa Tokyo 1908562 Japan Grad Univ Adv Studies Sch Multidisciplinary Sci Dept Stat Sci Tachikawa Tokyo 1908562 Japan

In the pre-Botzinger complex of the ventral medulla (preBotC), a variable pattern of inspiratory neuronal output and synchronous activation of inspiratory cells can be observed. However, it is not well known whether cellular activation patterns among inspiratory cells are variable or fixed. Here, we evaluated the activation sequence of inspiratory cells during individual rhythmic bursts using calcium imaging. Onset timing and peak timing of calcium fluctuations during rhythmic bursts in individual inspiratory cells were used to evaluate the activation sequence. The sequences of both timings changed stochastically in individual rhythmic bursts, although the sequences differed between the two timings even within the same rhythmic burst. The weak correlation between these two timings might indicate that the two parameters reflect different physiological events. Furthermore, a subset of inspiratory cells was found to initially activate in the sequences of successive rhythmic bursts. These results suggest that rhythmic activation of inspiratory cells occurs with a degree of loose regularity but is not invariable with respect to the sequence of either onset or peak timing. (C) 2015 Elsevier Ireland Ltd. All rights reserved.

关键词： Pre-Botzinger complex Calcium imaging activation sequence Rhythmic neuronal activity

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activation of Control Pins for Routing of Test Droplets within a Bi-Partitioned Digital Microfluidic Biochip 4

Activation of Control Pins for Routing of Test Droplets with...

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4th International Conference on Advances in Computing and Communications (ICACC)

作者： Das, Somak Roy, Sudip Dey, Sowvik Univ Burdwan Univ Inst Technol Dept Comp Sci & Engn Burdwan 713104 W Bengal India

ISBN: (纸本)9781479943630

Digital microfluidics based biochips is expected to play an important role towards point-of-care diagnostics, drug discovery, prevention of bio-terrorism and other bio-chemical applications. Design and testing of biochips always remained a challenging area of research. Structural testing of these bio-MEMS is ensured by smooth movements of test droplets within the microfluidic array. Partitioning the digital microfluidic array into clusters reduces the testing time. This paper proposes a novel scheme of activation of electrode-control pins based on existing allocation methods enabling movement of test droplets within a bi-partitioned digital microfluidic biochip.

关键词： digital microfluidics structural testing partitioning clusters electrode-control pins activation sequence

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