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https://www.readbyqxmd.com/read/28636811/performance-evaluation-of-gpu-parallelization-space-time-adaptive-algorithms-and-their-combination-for-simulating-cardiac-electrophysiology
#1
Rafael S Oliveira, Bernardo M Rocha, Denise Burgarelli, Wagner Meira, Christakis Constantinides, Rodrigo Weber Dos Santos
The use of computer models as a tool for the study and understanding of the complex phenomena of cardiac electrophysiology has attained increased importance nowadays. At the same time, the increased complexity of the biophysical processes translates into complex computational and mathematical models. In order to speed up cardiac simulations and to allow more precise and realistic uses, two different techniques have been traditionally exploited: parallel computing and sophisticated numerical methods. In this work, we combine a modern parallel computing technique based on multicore and graphics processing units (GPUs), and a sophisticated numerical method based on a new space-time adaptive algorithm...
June 21, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28633348/lifelong-arrhythmic-risk-stratification-in-arrhythmogenic-right-ventricular-cardiomyopathy-distribution-of-events-and-impact-of-periodical-reassessment
#2
Chiara Cappelletto, Davide Stolfo, Antonio De Luca, Bruno Pinamonti, Giulia Barbati, Alberto Pivetta, Marco Gobbo, Francesca Brun, Marco Merlo, Gianfranco Sinagra
Aims: The arrhythmic risk stratification of arrhythmogenic right ventricular cardiomyopathy (ARVC) remains controversial. We evaluated the long-term distribution of life-threatening arrhythmic events assessing the impact of periodical risk reassessment. Methods and results: Ninety-eight ARVC patients with no previous major ventricular arrhythmias were retrospectively analysed. Patients were assessed at baseline, at 22 [inter-quartile range (IQR) 16-26], 49 (IQR 41-55) and 97 months (IQR 90-108)...
June 13, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28630025/the-clock-is-ticking-ageing-of-the-circadian-system-from-physiology-to-cell-cycle
#3
REVIEW
Eva Terzibasi-Tozzini, Antonio Martinez-Nicolas, Alejandro Lucas-Sánchez
The circadian system is the responsible to organise the internal temporal order in relation to the environment of every process of the organisms producing the circadian rhythms. These rhythms have a fixed phase relationship among them and with the environment in order to optimise the available energy and resources. From a cellular level, circadian rhythms are controlled by genetic positive and negative auto-regulated transcriptional and translational feedback loops, which generate 24hour rhythms in mRNA and protein levels of the clock components...
June 16, 2017: Seminars in Cell & Developmental Biology
https://www.readbyqxmd.com/read/28624975/deleterious-acute-and-chronic-effects-of-bradycardic-right-ventricular-apex-pacing-consequences-for-arrhythmic-outcome
#4
T R G Stams, A Dunnink, W M van Everdingen, H D M Beekman, R van der Nagel, B Kok, M F A Bierhuizen, M J Cramer, M Meine, M A Vos
In the chronic complete atrioventricular (AV) block dog (CAVB) model, both bradycardia and altered ventricular activation due to the uncontrolled idioventricular rhythm contribute to ventricular remodeling and the enhanced susceptibility to Torsade de Pointes (TdP) arrhythmias. We investigated the effect of permanent bradycardic right ventricular apex (RVA) pacing on mechanical and electrical remodeling and TdP. In 23 anesthetized dogs, serial experiments were performed at sinus rhythm (SR), acutely after AV block (AAVB) and 3 weeks of remodeling CAVB at a fixed pacing rate of 60/min...
July 2017: Basic Research in Cardiology
https://www.readbyqxmd.com/read/28624712/classification-of-ecg-heartbeats-using-nonlinear-decomposition-methods-and-support-vector-machine
#5
Kandala N V P S Rajesh, Ravindra Dhuli
Classifying electrocardiogram (ECG) heartbeats for arrhythmic risk prediction is a challenging task due to minute variations in the amplitude, duration and morphology of the ECG signal. In this paper, we propose two feature extraction approaches to classify five types of heartbeats: normal, premature ventricular contraction, atrial premature contraction, left bundle branch block and right bundle branch block. In the first approach, ECG beats are decomposed into intrinsic mode functions (IMFs) using ensemble empirical mode decomposition (EEMD)...
June 15, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28623226/entraining-to-the-polar-day-circadian-rhythms-in-arctic-ground-squirrels
#6
Cory T Williams, Brian M Barnes, Lily Yan, C Loren Buck
Circadian systems are principally entrained to 24h light/dark cycles, but this cue is seasonally absent in polar environments. Although some resident polar vertebrates have weak circadian clocks and are seasonally arrhythmic, the arctic ground squirrel (AGS) maintains daily rhythms of physiology and behavior throughout the summer, which includes six weeks of constant daylight. Here, we show that persistent daily rhythms in AGS are maintained through a circadian system that readily entrains to the polar day yet remains insensitive to entrainment by rapid light-dark transitions, which AGS generate naturally due to their semi-fossorial behavior...
June 16, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28622331/in-silico-assessment-of-genetic-variation-in-kcna5-reveals-multiple-mechanisms-of-human-atrial-arrhythmogenesis
#7
Michael A Colman, Haibo Ni, Bo Liang, Nicole Schmitt, Henggui Zhang
A recent experimental study investigating patients with lone atrial fibrillation identified six novel mutations in the KCNA5 gene. The mutants exhibited both gain- and loss-of-function of the atrial specific ultra-rapid delayed rectifier K+ current, IKur. The aim of this study is to elucidate and quantify the functional impact of these KCNA5 mutations on atrial electrical activity. A multi-scale model of the human atria was updated to incorporate detailed experimental data on IKur from both wild-type and mutants...
June 16, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28621884/young-athletes-with-ventricular-premature-beats-continuing-or-not-intense-training-and-competition
#8
Attilio Parisi, Eliana Tranchita, Carlo Minganti, Fabio Sperandii, Emanuele Guerra, Leonardo Calò, Paolo Borrione, Fabio Pigozzi
INTRODUCTION: Isolated ventricular premature beats (VPBs) are commonly found during pre-participation screening in athletes. Currently the debate about the role of detraining in reducing the number of VPBs is still open. This study evaluated the arrhythmic risk in a population of young competitive athletes who showed VPBs during eligibility evaluation and that did not undergo detraining but continued practicing competitive sports. METHODS: 3746 consecutive subjects underwent pre-participation screening...
June 16, 2017: Scandinavian Journal of Medicine & Science in Sports
https://www.readbyqxmd.com/read/28620067/allele-specific-silencing-of-mutant-mrna-rescues-ultrastructural-and-arrhythmic-phenotype-in-mice-carriers-of-the-r4496c-mutation-in-the-ryanodine-receptor-gene-ryr2
#9
Rossana Bongianino, Marco Denegri, Andrea Mazzanti, Francesco Lodola, Alessandra Vollero, Simona Boncompagni, Silvia Fasciano, Giulia Rizzo, Damiano Mangione, Serena Barbaro, Alessia Di Fonso, Carlo Napolitano, Alberto Auricchio, Feliciano Protasi, Silvia G Priori
Rationale: Mutations in the cardiac Ryanodine Receptor gene (RYR2) cause dominant Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), a leading cause of sudden death in apparently healthy individuals exposed to emotions or physical exercise. Objective: We investigated the efficacy of allele specific silencing by RNA interference to prevent CPVT phenotypical manifestations in our dominant CPVT mice model carriers of the heterozygous mutation R4496C in RYR2Methods and Results: We developed an in vitro mRNA and protein-based assays to screen multiple siRNAs for their ability to selectively silence mutant RYR2-R4496C mRNA over the corresponding wild-type (WT) allele...
June 15, 2017: Circulation Research
https://www.readbyqxmd.com/read/28618772/efficacy-and-safety-of-pitavastatins-in-patients-with-acute-myocardial-infarction-livalo-in-acute-myocardial-infarction-study-lamis-ii
#10
Young Joon Hong, Myung Ho Jeong, Jang Ho Bae, Seok Kyu Oh, Seung Woon Rha, Seung Ho Hur, Sung Yun Lee, Sang Wook Kim, Kwang Soo Cha, In Ho Chae, Tae Hoon Ahn, Kee Sik Kim
Background/Aims: We evaluated the efficacy and safety and influence on glucose tolerance by different doses of pitavastatins in acute myocardial infarction (AMI) patients. Methods: Consecutive 1,101 AMI patients who were enrolled in Livalo in Acute Myocardial Infarction Study (LAMIS)-II were randomly assigned to receive either 2 mg of pitavastatin or 4 mg of pitavastatin orally per day. Primary efficacy endpoint was composite of cardiac death, nonfatal myocardial infarction, target-lesion revascularization, and hospitalization for unstable angina, heart failure or arrhythmic events at 12-month...
June 16, 2017: Korean Journal of Internal Medicine
https://www.readbyqxmd.com/read/28615472/neuronal-circadian-clock-protein-oscillations-are-similar-in-behaviourally-rhythmic-forager-honeybees-and-in-arrhythmic-nurses
#11
T Fuchikawa, K Beer, C Linke-Winnebeck, R Ben-David, A Kotowoy, V W K Tsang, G R Warman, E C Winnebeck, C Helfrich-Förster, G Bloch
Internal clocks driving rhythms of about a day (circadian) are ubiquitous in animals, allowing them to anticipate environmental changes. Genetic or environmental disturbances to circadian clocks or the rhythms they produce are commonly associated with illness, compromised performance or reduced survival. Nevertheless, some animals including Arctic mammals, open sea fish and social insects such as honeybees are active around-the-clock with no apparent ill effects. The mechanisms allowing this remarkable natural plasticity are unknown...
June 2017: Open Biology
https://www.readbyqxmd.com/read/28615142/overexpression-of-kcnj2-in-induced-pluripotent-stem-cell-derived-cardiomyocytes-for-the-assessment-of-qt-prolonging-drugs
#12
Min Li, Yasunari Kanda, Takashi Ashihara, Tetsuo Sasano, Yuji Nakai, Masami Kodama, Erina Hayashi, Yuko Sekino, Tetsushi Furukawa, Junko Kurokawa
Human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes hold great potentials to predict pro-arrhythmic risks in preclinical cardiac safety screening, although the hiPSC cardiomyocytes exhibit rather immature functional and structural characteristics, including spontaneous activity. Our physiological characterization and mathematical simulation showed that low expression of the inward-rectifier potassium (IK1) channel is a determinant of spontaneous activity. To understand impact of the low IK1 expression on the pharmacological properties, we tested if transduction of hiPSC-derived cardiomyocytes with KCNJ2, which encodes the IK1 channel, alters pharmacological response to cardiac repolarization processes...
May 27, 2017: Journal of Pharmacological Sciences
https://www.readbyqxmd.com/read/28614249/thymectomy-via-open-surgery-or-robotic-video-assisted-thoracic-surgery-can-a-recommendation-already-be-made
#13
Judith Buentzel, Carmen Straube, Judith Heinz, Christian Roever, Alexander Beham, Andreas Emmert, Marc Hinterthaner, Bernhard C Danner, Alexander Emmert
BACKGROUND: Robot-assisted minimally invasive surgery (RVATS) is a relatively new technique applied for thymectomies. Only few studies directly compare RVATS to the mainstay therapy, open surgery (sternotomy). METHODS: A systematic search of the literature was performed in October 2016. The meta-analysis includes studies comparing robotassisted and open thymectomy regarding operation time, length of hospitalization, intraoperative blood loss, and chest-in-tube days, postoperative complications, reoperation, arrhythmic events, pleural effusion, and postoperative bleeding...
June 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28610723/pathophysiology-of-paroxysmal-and-persistent-atrial-fibrillation-rotors-foci-and-fibrosis
#14
REVIEW
Dennis H Lau, Dominik Linz, Ulrich Schotten, Rajiv Mahajan, Prashanthan Sanders, Jonathan M Kalman
Recent advances in our understanding of the mechanisms underlying atrial fibrillation (AF) have further underscored the complex pathophysiological basis of the arrhythmia. It has become apparent that the current clinical classification of AF does not reflect the severity of the underlying atrial disease. Atrial fibrosis has been identified as the key structural change in different substrates that are responsible for the perpetuation of AF. Three-dimensional electroanatomical mapping and late gadolinium-enhanced magnetic resonance imaging are novel modalities that can be used to facilitate identification and quantitation of atrial fibrosis for improved delineation of the AF substrate...
May 24, 2017: Heart, Lung & Circulation
https://www.readbyqxmd.com/read/28609477/atrial-arrhythmogenicity-of-kcnj2-mutations-in-short-qt-syndrome-insights-from-virtual-human-atria
#15
Dominic G Whittaker, Haibo Ni, Aziza El Harchi, Jules C Hancox, Henggui Zhang
Gain-of-function mutations in KCNJ2-encoded Kir2.1 channels underlie variant 3 (SQT3) of the short QT syndrome, which is associated with atrial fibrillation (AF). Using biophysically-detailed human atria computer models, this study investigated the mechanistic link between SQT3 mutations and atrial arrhythmogenesis, and potential ion channel targets for treatment of SQT3. A contemporary model of the human atrial action potential (AP) was modified to recapitulate functional changes in IK1 due to heterozygous and homozygous forms of the D172N and E299V Kir2...
June 13, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28607609/efficacy-of-ranolazine-in-preventing-atrial-fibrillation-following-cardiac-surgery-results-from-a-meta-analysis
#16
REVIEW
Chintan Trivedi, Ankit Upadhyay, Kinjal Solanki
BACKGROUND: Atrial fibrillation (AF) is a common complication after cardiac surgery. Ranolazine is a Food and Drug Administration approved anti-ischemic drug, which also has anti-arrhythmic properties. Recent studies have demonstrated the benefit of ranolazine in preventing post-operative AF (POAF) in patients undergoing cardiac surgery. Hence, we performed a meta-analysis of published studies comparing ranolazine plus standard therapy versus standard therapy for POAF prevention in patients undergoing cardiac surgery...
June 2017: Journal of Arrhythmia
https://www.readbyqxmd.com/read/28606693/etiological-diagnosis-prognostic-significance-and-role-of-electrophysiological-study-in-patients-with-brugada-ecg-and-syncope
#17
Carla Giustetto, Natascia Cerrato, Enrico Ruffino, Elena Gribaudo, Chiara Scrocco, Lorella Barbonaglia, Francesca Bianchi, Miriam Bortnik, Guido Rossetti, Paula Carvalho, Riccardo Riccardi, Davide Castagno, Matteo Anselmino, Laura Bergamasco, Fiorenzo Gaita
BACKGROUND: Syncope is considered a risk factor for life-threatening arrhythmias in Brugada patients. Distinguishing a benign syncope from one due to ventricular arrhythmias is often difficult, unless an ECG is recorded during the episode. Aim of the study was to analyze the characteristics of syncopal episodes in a large population of Brugada patients and evaluate the role of electrophysiological study (EPS) and the prognosis in the different subgroups. METHODS AND RESULTS: One hundred ninety-five Brugada patients with history of syncope were considered...
August 15, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28606196/prescribing-an-automated-external-defibrillator-for-children-at-increased-risk-of-sudden-arrhythmic-death
#18
Karen A McLeod, Eileen Fern, Fiona Clements, Ruth McGowan
BACKGROUND: Automated external defibrillators can be life-saving in out-of-hospital cardiac arrest. OBJECTIVE: Our aim was to review our experience of prescribing automated external defibrillators for children at increased risk of sudden arrhythmic death. METHODS: We reviewed all automated external defibrillators issued by the Scottish Paediatric Cardiac Electrophysiology Service from 2005 to 2015. All parents were given resuscitation training according to the Paediatric Resuscitation Guidelines, including the use of the automated external defibrillator...
June 13, 2017: Cardiology in the Young
https://www.readbyqxmd.com/read/28605469/surgical-ablation-for-persistent-atrial-fibrillation-in-concomitant-cardiac-surgery-mid-long-term-result%C3%A2
#19
Wenda Gu, Huiming Guo, Cong Lu, Huanlei Huang, Jing Liu, Jian Liu, Bin Xie, Ruobin Wu, Jimei Chen, Jian Zhuang
OBJECTIVES: Surgical ablation is an option for patients with atrial fibrillation (AF) undergoing concomitant cardiac surgery. This study aims to evaluate the outcome of surgical ablation during concomitant cardiac surgery and to identify the independent predictors for a primary end-point consisting of AF or atrial flutter (AFL) recurrence, death, permanent pacemaker implantation and necessity for anti-arrhythmic drugs and the effects of reintervention for AF/AFL recurrence. METHODS: A retrospective analysis was performed for 1028 patients who underwent surgical ablation during concomitant cardiac surgery from October 2004 to April 2015...
June 12, 2017: European Journal of Cardio-thoracic Surgery
https://www.readbyqxmd.com/read/28599667/multipolar-pacing-by-cardiac-resynchronization-therapy-with-a-defibrillators-treatment-in-type-2-diabetes-mellitus-failing-heart-patients-impact-on-responders-rate-and-clinical-outcomes
#20
Celestino Sardu, Michelangela Barbieri, Matteo Santamaria, Valerio Giordano, Cosimo Sacra, Pasquale Paolisso, Alessandro Spirito, Raffaele Marfella, Giuseppe Paolisso, Maria Rosaria Rizzo
BACKGROUND: Type 2 diabetes mellitus (T2DM) is a multi factorial disease, affecting clinical outcomes in failing heart patients treated by cardiac resynchronization therapy with a defibrillator (CRT-d). METHODS: One hundred and ninety-five T2DM patients received a CRT-d treatment. Randomly the study population received a CRT-d via multipolar left ventricle (LV) lead pacing (n 99, multipolar group), vs a CRT-d via bipolar LV pacing (n 96, bipolar group). These patients were followed by clinical, and instrumental assessment, and telemetric device control at follow up...
June 9, 2017: Cardiovascular Diabetology
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