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https://www.readbyqxmd.com/read/28919217/population-based-beat-to-beat-qt-analysis-from-holter-recordings-in-the-long-qt-syndrome
#1
Alex Page, Scott McNitt, Xiaojuan Xia, Wojciech Zareba, Jean-Philippe Couderc
The increasing dissemination of wearable ECG recorders (e.g. Holter, patches, and strap sensors) enables the acquisition of large amounts of data during long periods of time. However, the clinical value of these long-term continuous recordings is hindered by the lack of automatic tools to extract clinically relevant information (other than non-sinus and life-threatening rhythms) from such long-term data, particularly when targeting population-based research. In this work, we propose and test a new tool for analyzing beat-to-beat interval measurements and extracting features from Holter ECGs...
August 10, 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/28912206/clinical-yield-of-familial-screening-after-sudden-death-in-young-subjects-the-french-experience
#2
Pauline Quenin, Florence Kyndt, Philippe Mabo, Jacques Mansourati, Dominique Babuty, Aurélie Thollet, Béatrice Guyomarch, Richard Redon, Julien Barc, Jean-Jacques Schott, Frederic Sacher, Vincent Probst, Jean Baptiste Gourraud
BACKGROUND: After sudden cardiac death with negative autopsy, clinical screening of relatives identifies a high proportion of inherited arrhythmia syndrome. However, the efficacy of this screening in families not selected by autopsy has never been assessed. We aim to investigate the value of clinical screening in relatives of all subjects who died suddenly before 45 years of age. METHODS AND RESULTS: One hundred and three consecutive families who experienced unexplained sudden cardiac death before 45 years of age were included from May 2009 to December 2014 in a prospective multicenter registry...
September 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28912179/classification-epidemiology-and-global-burden-of-cardiomyopathies
#3
REVIEW
William J McKenna, Barry J Maron, Gaetano Thiene
In the past 25 years, major advances were achieved in the nosography of cardiomyopathies, influencing the definition and taxonomy of this important chapter of cardiovascular disease. Nearly, 50% of patients dying suddenly in childhood or adolescence or undergoing cardiac transplantation are affected by cardiomyopathies. Novel cardiomyopathies have been discovered (arrhythmogenic, restrictive, and noncompacted) and added to update the World Health Organization classification. Myocarditis has also been named inflammatory cardiomyopathy...
September 15, 2017: Circulation Research
https://www.readbyqxmd.com/read/28904293/characteristics-of-electromechanical-window-in-anesthetized-rabbit-models-of-short-qt-and-long-qt-syndromes
#4
Vudhiporn Limprasutr, Nakkawee Saengklub, Pradtana Meedech, Anusak Kijtawornrat, Robert L Hamlin
The current regulatory guidelines recommend the use of QT interval to assess the risk of arrhythmogenic potential of new chemical entities. Recently, the electromechanical window (EMW), the difference in duration between electrical and mechanical systole, has been proposed as markers for drug-induced torsades de pointes (TdP); however, data of EMW in short QT model are not available. This study aimed to characterize the EMW as a marker for drug-induced ventricular arrhythmias in anesthetized rabbit model of long QT syndrome type 2 (LQT2) and short QT syndrome (SQTS) infused with reference compounds known to lengthen or shorten QT intervals...
2017: Journal of Toxicological Sciences
https://www.readbyqxmd.com/read/28901586/long-term-effects-of-cardiac-resynchronization-therapy-on-electrical-remodeling-in-heart-failure-a-prospective-study
#5
Bharatraj Banavalikar, Anees Thajudeen, Narayanan Namboodiri, Krishna Kumar Mohanan Nair, Abhilash Srivilasam Pushpangadhan, Ajit Kumar Valaparambil
INTRODUCTION: Effects of cardiac resynchronization therapy (CRT) on arrhythmogenicity and sudden death have not been fully ascertained. CRT has been shown to increase transmural dispersion of repolarization (TDR) immediately on implantation, that may favorably remodel on long-term follow-up. However, such a hypothesis has not been prospectively evaluated. METHODS AND RESULTS: We included 35 consecutive patients who underwent CRT implantation between September 2013 & August 2014 (mean age 56...
September 13, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28898267/depolarization-of-the-conductance-voltage-relationship-in-the-nav1-5-mutant-e1784k-is-due-to-altered-fast-inactivation
#6
Colin H Peters, Alec Yu, Wandi Zhu, Jonathan R Silva, Peter C Ruben
E1784K is the most common mixed long QT syndrome/Brugada syndrome mutant in the cardiac voltage-gated sodium channel NaV1.5. E1784K shifts the midpoint of the channel conductance-voltage relationship to more depolarized membrane potentials and accelerates the rate of channel fast inactivation. The depolarizing shift in the midpoint of the conductance curve in E1784K is exacerbated by low extracellular pH. We tested whether the E1784K mutant shifts the channel conductance curve to more depolarized membrane potentials by affecting the channel voltage-sensors...
2017: PloS One
https://www.readbyqxmd.com/read/28894151/the-effects-of-ageing-and-adrenergic-challenge-on-electrocardiographic-phenotypes-in-a-murine-model-of-long-qt-syndrome-type-3
#7
Karan R Chadda, Shiraz Ahmad, Haseeb Valli, Ingrid den Uijl, Ali Bak Al-Hadithi, Samantha C Salvage, Andrew A Grace, Christopher L-H Huang, Kamalan Jeevaratnam
Long QT Syndrome 3 (LQTS3) arises from gain-of-function Nav1.5 mutations, prolonging action potential repolarisation and electrocardiographic (ECG) QT interval, associated with increased age-dependent risk for major arrhythmic events, and paradoxical responses to β-adrenergic agents. We investigated for independent and interacting effects of age and Scn5a+/ΔKPQ genotype in anaesthetised mice modelling LQTS3 on ECG phenotypes before and following β-agonist challenge, and upon fibrotic change. Prolonged ventricular recovery was independently associated with Scn5a+/ΔKPQ and age...
September 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28892643/comparison-of-the-effects-of-i-sub-k-ach-sub-i-sub-kr-sub-and-i-sub-na-sub-block-in-conscious-dogs-with-atrial-fibrillation-and-on-action-potentials-in-remodeled-atrial-trabeculae
#8
Viktor Juhász, Tibor Hornyik, Attila Benák, Norbert Nagy, Zoltan Husti, Robert Pap, László Sághy, László Virág, András Varró, István Baczkó
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and a major cause of morbidity and mortality. Traditional antiarrhythmic agents used for restoration of sinus rhythm have limited efficacy in long-term AF and they may possess ventricular proarrhythmic adverse effects, especially in patients with structural heart disease. The acetylcholin receptor-activated potassium channel (I<sub>K,ACh</sub>) represents an atrial-selective target for future AF management. We investigated the effects of the I<sub>K,ACh</sub> blocker tertiapin-Q (TQ), a derivative of the honeybee toxin tertiapin, on chronic atrial tachypacing induced AF in conscious dogs, without the influence of anesthetics that modulate a number of cardiac ion channels...
September 11, 2017: Canadian Journal of Physiology and Pharmacology
https://www.readbyqxmd.com/read/28869094/effect-of-age-and-gender-on-the-qtc-interval-in-healthy-individuals-and-patients-with-long-qt-syndrome
#9
REVIEW
Arja Suzanne Vink, Sally-Ann B Clur, Arthur A M Wilde, Nico A Blom
Age- and gender-related differences in QTc-interval are most likely the result of changes in sex-specific hormones. Although the exact mechanisms and pathophysiology of sex hormones on the QTc-interval are not known, testosterone appears to shorten the QTc-interval. In females, however, there is a more complex interaction between progesterone and estrogen. In patients with an impaired repolarization, such as long-QT syndrome (LQTS), the effect of these sex hormones on the QTc-interval is more pronounced with a differing sensitivity between the LQTS genotypes...
August 3, 2017: Trends in Cardiovascular Medicine
https://www.readbyqxmd.com/read/28864717/impact-of-presynaptic-sympathetic-imbalance-in-long-qt-syndrome-by-positron-emission-tomography
#10
Sven Zumhagen, Alexis Vrachimis, Lars Stegger, Peter Kies, Christian Wenning, Marko Ernsting, Jovanca Müller, Guiscard Seebohm, Matthias Paul, Klaus Schäfers, Birgit Stallmeyer, Michael Schäfers, Eric Schulze-Bahr
OBJECTIVE: We investigated the impact of cardiac presynaptic norepinephrine recycling in patients with long-QT syndrome (LQTS) using positron emission tomography (PET) with (11)C-meta-hydroxyephedrine ([(11)C]mHED-PET). METHODS: [(11)C]mHED-PET was performed in 25 patients with LQTS (LQT1: n=14; LQT2: n=11) and 20 healthy controls and correlated with clinical parameters. [(11)C]mHED-PET images were analysed for global and regional retention indices (RI) and washout rates (WO) reflecting dynamic parameters of the tracer activity...
September 1, 2017: Heart: Official Journal of the British Cardiac Society
https://www.readbyqxmd.com/read/28863167/the-development-and-validation-of-an-easy-to-use-automatic-qt-interval-algorithm
#11
Ben J M Hermans, Arja S Vink, Frank C Bennis, Luc H Filippini, Veronique M F Meijborg, Arthur A M Wilde, Laurent Pison, Pieter G Postema, Tammo Delhaas
BACKGROUND: To evaluate QT-interval dynamics in patients and in drug safety analysis, beat-to-beat QT-interval measurements are increasingly used. However, interobserver differences, aberrant T-wave morphologies and changes in heart axis might hamper accurate QT-interval measurements. OBJECTIVE: To develop and validate a QT-interval algorithm robust to heart axis orientation and T-wave morphology that can be applied on a beat-to-beat basis. METHODS: Additionally to standard ECG leads, the root mean square (ECGRMS), standard deviation and vectorcardiogram were used...
2017: PloS One
https://www.readbyqxmd.com/read/28858645/simulation-study-of-the-ionic-mechanisms-underlying-torsade-de-pointes-in-a-2d-cardiac-tissue
#12
Ponnuraj Kirthi Priya, M Ramasubba Reddy
BACKGROUND: To understand the ionic mechanism behind the genesis of Torsade de Pointes (TdP) occurring with long QT syndrome 2 (LQTS2) in a remodelled transmural tissue. METHODS: The TP06 model is used to simulate the electrical activity of cells in a 2D transmural ventricular model. LQTS2 is realised by reducing the potassium current (IKr) to 0.5 in each cell. Each cell of the tissue is remodelled by increasing the conductance of calcium current (GCaL). The above two factors make the cells prone to early after depolarizations (EADs) development...
August 24, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28857516/modeling-of-the-herg-k-channel-blockage-using-online-chemical-database-and-modeling-environment-ochem
#13
Xiao Li, Yuan Zhang, Huanhuan Li, Yong Zhao
Human ether-a-go-go related gene (hERG) K+ channel plays an important role in cardiac action potential. Blockage of hERG channel may result in long QT syndrome (LQTS), even cause sudden cardiac death. Many drugs have been withdrawn from the market because of the serious hERG-related cardiotoxicity. Therefore, it is quite essential to estimate the chemical blockage of hERG in the early stage of drug discovery. In this study, a diverse set of 3721 compounds with hERG inhibition data was assembled from literature...
August 30, 2017: Molecular Informatics
https://www.readbyqxmd.com/read/28856762/pregbalin-induced-recurrent-syncopal-attacks-with-prolong-qt-interval
#14
Adem Adar, Fahri Cakan, Orhan Önalan
Long QT syndrome may lead to fatal dysrhythmia. Prolongation of QT interval due to pregabalin has been shown in rats and no data is available in humans. We report a 80-year-old female patient using pregabalin. She was presented to emergency room with syncope attacks. Her admission electrocardiography demonstrated prolonged QT interval. After excluding the possible causes of the long QT syndrome, we attributed prolonged QT interval to pregabalin therapy. After discontinuation of pregabalin QT interval returned to normal range and patient experienced no further syncope attacks...
August 30, 2017: Annals of Noninvasive Electrocardiology
https://www.readbyqxmd.com/read/28851566/-long-qt-syndrome-due-to-fluoxetine
#15
C Canet Fajas, L Urieta González, J A Ibañez Pérez de Viñaspre
No abstract text is available yet for this article.
August 26, 2017: Semergen
https://www.readbyqxmd.com/read/28846720/the-association-of-long-term-glycaemic-variability-versus-sustained-chronic-hyperglycaemia-with-heart-rate-corrected-qt-interval-in-patients-with-type-2-diabetes
#16
Jian-Bin Su, Xiao-Hua Yang, Xiu-Lin Zhang, Hong-Li Cai, Hai-Yan Huang, Li-Hua Zhao, Feng Xu, Tong Chen, Xing-Bo Cheng, Xue-Qin Wang, Yan Lu
OBJECTIVES: Prolonged heart rate-corrected QT(QTc) interval is related to ventricular arrhythmia and cardiovascular mortality, with considerably high prevalence of type 2 diabetes. Additionally, long-term glycaemic variability could be a significant risk factor for diabetic complications in addition to chronic hyperglycaemia. We compared the associations of long-term glycaemic variability versus sustained chronic hyperglycaemia with the QTc interval among type 2 diabetes patients. METHODS: In this cross-sectional study, 2904 type 2 diabetes patients were recruited who had undergone at least four fasting plasma glucose (FPG) and 2-hour postprandial plasma glucose (PPG) measurements (at least once for every 3 months, respectively) during the preceding year...
2017: PloS One
https://www.readbyqxmd.com/read/28839201/development-of-an-ensemble-kalman-filter-data-assimilation-system-for-the-venusian-atmosphere
#17
Norihiko Sugimoto, Akira Yamazaki, Toru Kouyama, Hiroki Kashimura, Takeshi Enomoto, Masahiro Takagi
The size and mass of Venus is similar to those of the Earth; however, its atmospheric dynamics are considerably different and they are poorly understood due to limited observations and computational difficulties. Here, we developed a data assimilation system based on the local ensemble transform Kalman filter (LETKF) for a Venusian Atmospheric GCM for the Earth Simulator (VAFES), to make full use of the observational data. To examine the validity of the system, two datasets were assimilated separately into the VAFES forecasts forced with solar heating that excludes the diurnal component Qz; one was created from a VAFES run forced with solar heating that includes the diurnal component Qt, whereas the other was based on observations made by the Venus Monitoring Camera (VMC) onboard the Venus Express...
August 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28827789/positional-cloning-of-quantitative-trait-nucleotides-for-blood-pressure-and-cardiac-qt-interval-by-targeted-crispr-cas9-editing-of-a-novel-long-non-coding-rna
#18
Xi Cheng, Harshal Waghulde, Blair Mell, Eric E Morgan, Shondra M Pruett-Miller, Bina Joe
Multiple GWAS studies have reported strong association of cardiac QT-interval to a region on HSA17. Interestingly, a rat locus homologous to this region is also linked to QT-intervals. The high resolution positional mapping study located the rat QT-interval locus to a <42.5kb region on RNO10. This region contained no variants in protein-coding sequences, but a prominent contiguous 19bp indel polymorphism was noted within a novel predicted long non-coding RNA (lncRNA), which we named as Rffl-lnc1. To assess the candidacy of this novel lncRNA on QT-interval, targeted CRISPR/Cas9 based genome-engineering approaches were applied on the rat strains used to map this locus...
August 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28820736/long-qt-syndrome-diagnosed-in-two-sisters-with-propionic-acidemia-a-case-report
#19
Ensar Duras, Ahmet İrdem, Ozan Özkaya
Propionic acidemia (PA) is a rare autosomal recessive metabolic disorder caused by deficiency of the mitochondrial enzyme propionyl-CoA carboxylase (PCC). This disorder mostly progresses with episodes of metabolic acidosis. Cardiomyopathy is among the cardiac complications known to occur during metabolic decompensation episodes. However, several recent papers emphasized the association of PA and long QT syndrome (LQTS) which may lead to extremely serious and fatal consequences. In this report, we describe two sisters with PA who have prolonged QT duration that were incidentally detected in an outpatient setting...
August 18, 2017: Journal of Pediatric Endocrinology & Metabolism: JPEM
https://www.readbyqxmd.com/read/28815011/genomic-upregulation-of-cardiac-cav1-2%C3%AE-and-ncx1-by-estrogen-in-women
#20
Rita Papp, Glenna C L Bett, Agnieszka Lis, Randall L Rasmusson, István Baczkó, András Varró, Guy Salama
BACKGROUND: Women have a higher risk of lethal arrhythmias than men in long QT syndrome type 2 (LQTS2), but the mechanisms remain uncertain due to the limited availability of healthy control human tissue. We have previously reported that in female rabbits, estrogen increases arrhythmia risk in drug-induced LQTS2 by upregulating L-type Ca(2+) (ICa,L) and sodium-calcium exchange (INCX) currents at the base of the epicardium by a genomic mechanism. This study investigates if the effects of estrogen on rabbit ICa,L and INCX apply to human hearts...
2017: Biology of Sex Differences
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