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https://www.readbyqxmd.com/read/28438721/clinical-profile-and-mutation-spectrum-of-long-qt-syndrome-in-saudi-arabia-the-impact-of-consanguinity
#1
Zuhair N Al-Hassnan, Majid Al-Fayyadh, Bander Al-Ghamdi, Azam Shafquat, Yaseen Mallawi, Faten Al-Hadeq, Sahar Tulbah, Zarghuna Ma Shinwari, Abdulrahman Almesned, Ali Alakhfash, Fadel Al Fadly, Ahmed S Hersi, Abdullah Alhayani, Amal Al-Hashem, Dia Arafah, Nduna Dzimiri, Brian Meyer, Monther Rababh, Waleed Al-Manea
BACKGROUND: Congenital long QT syndrome (LQTS) is an inherited potentially fatal arrhythmogenic disorder. At least 16 genes have been implicated in LQTS; the yield of genetic analysis of 3 genes (KCNQ1, KCNH2, and SCN5A) is about 70% with KCNQ1 mutations accounting for ∼50% of positive cases. LQTS is mostly inherited in an autosomal dominant pattern. Systemic analysis of LQTS has not been previously conducted in a population with a high degree of consanguinity. OBJECTIVES: We aim to describe the clinical and molecular profiles of LQTS in the highly consanguineous Saudi population...
April 21, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28436171/sex-and-regional-differences-in-rabbit-right-ventricular-l-type-calcium-current-levels-and-mathematical-modeling-of-arrhythmia-vulnerability
#2
Zane M Kalik, Joshua L Mike, Cassandra Slipski, Moriah Wright, Jozsi Z Jalics, Mark D Womble
Previous studies have shown that adult rabbit left ventricular myocytes exhibit sex and regional differences in L-type calcium current (ICa-L ) levels that contribute to increased susceptibility to arrhythmogenic early afterdepolarizations (EADs). We used patch clamp recordings from isolated adult male and female rabbit right ventricular myocytes to determine apex-base differences in ICa-L density, and mathematical modeling to examine ICa-L contribution to EAD formation. Current density measured at 0 mV in female base myocytes was 67% higher than male base myocytes and 55% higher than female apex myocytes...
April 24, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28434968/cardiac-contractility-correction-strategies-applied-to-telemetry-data-from-a-hesi-sponsored-consortium
#3
Emmanuel Boulay, Michael K Pugsley, Vincent Jacquemet, Alain Vinet, Michael V Accardi, Maxim Soloviev, Eric Troncy, Jennifer M Doyle, Jennifer Beck Pierson, Simon Authier
INTRODUCTION: QT has a long history of heart rate (HR) correction but limited investigations have been undertaken to assess the impact of cardiovascular parameters on left ventricular (LV) contractility in drug safety testing. Cardiac contractility is affected by preload (Cyon-Frank-Starling law), afterload (Anrep effect) and HR (Bowditch effect). We evaluated multi-parameter correction methods to help with dP/dtmax interpretation. METHODOLOGY: Modeling was undertaken using data from dogs in single or double 4×4 Latin square studies...
April 20, 2017: Journal of Pharmacological and Toxicological Methods
https://www.readbyqxmd.com/read/28433559/the-kcnh2-ivs9-28a-g-mutation-causes-aberrant-isoform-expression-and-herg-trafficking-defect-in-cardiomyocytes-derived-from-patients-affected-by-long-qt-syndrome-type-2
#4
Manuela Mura, Ashish Mehta, Chrishan J Ramachandra, Rita Zappatore, Federica Pisano, Maria Chiara Ciuffreda, Vincenzo Barbaccia, Lia Crotti, Peter J Schwartz, Winston Shim, Massimiliano Gnecchi
BACKGROUND: Long QT Syndrome type 2 (LQT2) is caused by mutations in the KCNH2 gene that encodes for the α-subunit (hERG) of the ion channel conducting the rapid delayed rectifier potassium current (IKr). We have previously identified a disease causing mutation (IVS9-28A/G) in the branch point of the splicing of KCNH2 intron 9. However, the mechanism through which this mutation causes the disease is unknown. METHODS AND RESULTS: We generated human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from fibroblasts of two IVS9-28A/G mutation carriers...
April 12, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28431243/cryo-em-structure-of-the-open-human-ether-%C3%A3-go-go-related-k-channel-herg
#5
Weiwei Wang, Roderick MacKinnon
The human ether-à-go-go-related potassium channel (hERG, Kv11.1) is a voltage-dependent channel known for its role in repolarizing the cardiac action potential. hERG alteration by mutation or pharmacological inhibition produces Long QT syndrome and the lethal cardiac arrhythmia torsade de pointes. We have determined the molecular structure of hERG to 3.8 Å using cryo-electron microscopy. In this structure, the voltage sensors adopt a depolarized conformation, and the pore is open. The central cavity has an atypically small central volume surrounded by four deep hydrophobic pockets, which may explain hERG's unusual sensitivity to many drugs...
April 20, 2017: Cell
https://www.readbyqxmd.com/read/28431056/long-term-outcome-of-transvenous-pacemaker-implantation-in-infants-a-retrospective-cohort-study
#6
Laura M Vos, Janneke A E Kammeraad, Matthias W Freund, Andreas C Blank, Johannes M P J Breur
Aim: Evaluation of long-term outcome of transvenous pacemaker (PM) implantation in infants. Methods and Results: A retrospective analysis of all transvenous PM implantations in infants <10 kg between September 1997 and October 2001 was made. Indications for PM implantation, age at implantation, and determinants of long-term outcome including cardiac function, PM function, and PM (system) complications were noted. Seven patients underwent transvenous VVI(R) PM implantation...
April 1, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28429460/automated-t-wave-analysis-can-differentiate-acquired-qt-prolongation-from-congenital-long-qt-syndrome
#7
Alan Sugrue, Peter A Noseworthy, Vaclav Kremen, J Martijn Bos, Bo Qiang, Ram K Rohatgi, Yehu Sapir, Zachi I Attia, Peter Brady, Pedro J Caraballo, Samuel J Asirvatham, Paul A Friedman, Michael J Ackerman
BACKGROUND: Prolongation of the QT on the surface electrocardiogram can be due to either genetic or acquired causes. Distinguishing congenital long QT syndrome (LQTS) from acquired QT prolongation has important prognostic and management implications. We aimed to investigate if quantitative T-wave analysis could provide a tool for the physician to differentiate between congenital and acquired QT prolongation. METHODS: Patients were identified through an institution-wide computer-based QT screening system which alerts the physician if the QTc ≥ 500 ms...
April 21, 2017: Annals of Noninvasive Electrocardiology
https://www.readbyqxmd.com/read/28416468/cardiac-transplantation-in-children-and-adolescents-with-long-qt-syndrome
#8
Angela M Kelle, J Martijn Bos, Susan P Etheridge, Bryan C Cannon, Randall M Bryant, Jonathan N Johnson, Michael J Ackerman
BACKGROUND: Long QT syndrome (LQTS) is a potentially lethal, yet highly treatable, cardiac channelopathy. Cardiac transplantation has been reported anecdotally for patients with severe LQTS refractory to standard therapies. OBJECTIVE: We evaluated the incidence and risk factors for cardiac transplantation among children evaluated and treated in an LQTS specialty center. METHODS: This was a retrospective review of 349 children with LQTS (mean age at diagnosis, 8...
April 14, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28413954/computational-models-for-understanding-of-structure-function-and-pharmacology-of-the-cardiac-potassium-channel-kv11-1-herg
#9
Sören Wacker, Sergei Yu Noskov, Laura L Perissinotti
The rapid delayed rectifier current IKr is one of the major K+ currents involved into repolarization of the human cardiac action potential. Various inherited or drug-induced forms of the long QT syndrome (LQTS) in humans are linked to functional and structural modifications in the IKr conducting channels. IKr is carried by the potassium channel Kv11.1 encoded by the gene KCNH2 (commonly referred to as human ether-a-go-go-related gene or hERG) [1][2]. The first necessary step for predicting emergent drug effects on the heart is determining and modeling the binding thermodynamics and kinetics of primary and major off-target drug interactions with subcellular targets...
April 14, 2017: Current Topics in Medicinal Chemistry
https://www.readbyqxmd.com/read/28412158/lidocaine-attenuation-testing-an-in-vivo-investigation-of-putative-lqt3-associated-variants-in-the-scn5a-encoded-sodium-channel
#10
M D Heather N Anderson, J Martijn Bos, Jamie D Kapplinger, Jana M Meskill, Dan Ye, Michael J Ackerman
BACKGROUND: Long QT type 3 (LQT3) accounts for 5-10% of LQTS and results from gain-of-function mutations in the SCN5A-encoded sodium channel. Nearly 2% of healthy individuals host rare SCN5A variants of uncertain significance (VUS). Distinction of true LQT3-causative mutations from background genetic noise is essential. OBJECTIVE: This study was designed to assess the utility of the lidocaine attenuation test (LAT) in evaluating patients with possible LQT3. METHODS: We reviewed LAT results and medical records for 25 patients with a possible LQT3-associated SCN5A variant...
April 12, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28407228/deleterious-protein-altering-mutations-in-the-scn10a-voltage-gated-sodium-channel-gene-are-associated-with-prolonged-qt
#11
Maen D Abou Ziki, Sara B Seidelmann, Emily Smith, Gourg Atteya, Yuexin Jiang, Rodolfo Gil Fernandes, Mark A Marieb, Joseph G Akar, Arya Mani
Long QT syndrome (LQT) is a pro-arrhythmogenic condition with life threatening complications. Fifteen genes have been associated with congenital LQT however, the genetic causes remain unknown in more than 20% of cases. Eighteen patients with history of palpitations, presyncope, syncope and prolonged QT were referred to the Yale Cardiovascular Genetics Program. All subjects underwent whole exome sequencing (WES) followed by confirmatory Sanger sequencing. Mutation burden analysis was carried out using WES data from sixteen subjects with no identifiable cause of LQT...
April 13, 2017: Clinical Genetics
https://www.readbyqxmd.com/read/28405995/recurrent-ventricular-tachycardia-due-to-long-qt-syndrome
#12
Rambabu Singh, Kshitiz Nath, Archana
Long QT syndrome (LQTS) is a rare inherited heart condition in which delayed repolarization of the heart following a heartbeat, increases the risk of episodes of Torsades de pointes (TdP, a form of irregular heartbeat that originates from the ventricles). These episodes may lead to palpitations, fainting, and sudden death due to ventricular fibrillation. Episodes may be provoked by various stimuli, depending on the subtype of the condition. We are reporting a case of 37 years old male whom we diagnosed to have long QT syndrome on the basis of clinical and ECG findings...
December 2016: Journal of the Association of Physicians of India
https://www.readbyqxmd.com/read/28402425/therapeutic-approaches-for-long-qt-syndrome-type-3-an-update
#13
Arthur A M Wilde, Carol Ann Remme
No abstract text is available yet for this article.
April 11, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28400316/glucose-ingestion-causes-cardiac-repolarization-disturbances-in-type-1-long-qt-syndrome-patients-and-healthy-subjects
#14
Louise Hyltén-Cavallius, Eva W Iepsen, Michael Christiansen, Claus Graff, Allan Linneberg, Oluf Pedersen, Jens J Holst, Torben Hansen, Signe S Torekov, Jørgen K Kanters
BACKGROUND: Both hypo- and severe hyperglycaemia constitute known risk factors for cardiac repolarization changes potentially leading to malignant arrhythmias. Patients with loss of function mutations in KCNQ1 are characterized by long QT-syndrome (LQTS) and may be at increased risk of glucose-induced repolarization disturbances. OBJECTIVE: We hypothezised that KCNQ1 LQTS patients are at particular risk of cardiac repolarization changes during the relative hyperglycaemia that occurs after an oral glucose load...
April 8, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28392310/the-role-of-the-autonomic-nervous-system-in-arrhythmias-and-sudden-cardiac-death
#15
REVIEW
Sonia Franciosi, Frances K G Perry, Thomas M Roston, Kathryn R Armstrong, Victoria E Claydon, Shubhayan Sanatani
The autonomic nervous system (ANS) is complex and plays an important role in cardiac arrhythmia pathogenesis. A deeper understanding of the anatomy and development of the ANS has shed light on its involvement in cardiac arrhythmias. Alterations in levels of Sema-3a and NGF, both growth factors involved in innervation patterning during development of the ANS, leads to cardiac arrhythmias. Dysregulation of the ANS, including polymorphisms in genes involved in ANS development, have been implicated in sudden infant death syndrome...
March 31, 2017: Autonomic Neuroscience: Basic & Clinical
https://www.readbyqxmd.com/read/28391114/genotype-phenotype-dilemma-in-a-case-of-sudden-cardiac-death-with-the-e1053k-mutation-and-a-deletion-in-the-scn5a-gene
#16
T Jenewein, B M Beckmann, S Rose, H H Osterhues, U Schmidt, C Wolpert, P Miny, C Marschall, M Alders, C R Bezzina, A A M Wilde, S Kääb, S Kauferstein
Mutations in the cardiac sodium channel gene SCN5A may result in various arrhythmia syndromes such as long QT syndrome type 3 (LQTS), Brugada syndrome (BrS), sick sinus syndrome (SSS), cardiac conduction diseases (CCD) and possibly dilated cardiomyopathy (DCM). In most of these inherited cardiac arrhythmia syndromes the phenotypical expression may range from asymptomatic phenotypes to sudden cardiac death (SCD). A 16-year-old female died during sleep. Autopsy did not reveal any explanation for her death and a genetic analysis was performed...
March 20, 2017: Forensic Science International
https://www.readbyqxmd.com/read/28383310/short-term-variability-of-repolarization-is-superior-to-other-repolarization-parameters-in-the-evaluation-of-diverse-antiarrhythmic-interventions-in-the-chronic-av-block-dog
#17
A Bossu, R Varkevisser, Hdm Beekman, Mjc Houtman, Mag van der Heyden, M A Vos
Short-term variability (STV), to quantify beat-to-beat variability of repolarization (BVR), is a surrogate parameter that reliably identifies proarrhythmic risk in preclinical models. Examples include not only the use in the chronic atrioventricular block (CAVB) dog model whereby it was developed, but also in vulnerable patients with heart failure or drug-induced long QT syndrome. In the CAVB dog model, STV can specifically distinguish between safe and unsafe drugs in proarrhythmic screening. Conversely, this dog model also offers the possibility to evaluate antiarrhythmic strategies in a setting of Torsades de Pointes (TdP) induction with a standard IKr inhibitor...
March 31, 2017: Journal of Cardiovascular Pharmacology
https://www.readbyqxmd.com/read/28382321/electrophysiological-mechanisms-of-long-and-short-qt-syndromes
#18
REVIEW
Gary Tse, Yin Wah Fiona Chan, Wendy Keung, Bryan P Yan
The QT interval on the human electrocardiogram is normally in the order of 450 ms, and reflects the summated durations of action potential (AP) depolarization and repolarization of ventricular myocytes. Both prolongation and shortening in the QT interval have been associated with ventricular tachy-arrhythmias, which predispose affected individuals to sudden cardiac death. In this article, the molecular determinants of the AP duration and the causes of long and short QT syndromes (LQTS and SQTS) are explored...
March 2017: IJC Heart & Vasculature
https://www.readbyqxmd.com/read/28379067/mercury-omega-3-fatty-acids-and-seafood-intake-are-not-associated-with-heart-rate-variability-or-qt-interval
#19
Charles Miller, Roxanne Karimi, Susan Silbernagel, Danielle Kostrubiak, Frederick Schiavone, Qiao Zhang, Jie Yang, Eric Rashba, Jaymie R Meliker
Mercury (Hg), eicosapentanoic acid (EPA), and docosahexaenoic acid (DHA) concentrations differ across seafood types. Our aim was to investigate the association of Hg, EPA and DHA, as well as avid consumption of diverse seafood types on cardiovascular variables heart rate variability (HRV) and QT interval duration (QTc) in a contemporary population. We measured HRV and QTc by Holter monitor, EPA and DHA in plasma, total Hg in whole blood, and possible confounders in ninety-four avid seafood consumers from Long Island, NY...
April 5, 2017: Archives of Environmental & Occupational Health
https://www.readbyqxmd.com/read/28369767/multiple-targets-for-flecainide-action-implications-for-cardiac-arrhythmogenesis
#20
REVIEW
Samantha C Salvage, Karthik H Chandrasekharan, Kamalan Jeevaratnam, Angela F Dulhunty, Andrew J Thompson, Antony P Jackson, Christopher L-H Huang
Flecainide suppresses cardiac tachyarrhythmias including paroxysmal atrial fibrillation, supraventricular tachycardia, arrhythmic long QT syndromes (LQTS), as well as the Ca(2+) -mediated, catecholaminergic polymorphic ventricular, tachycardia (CPVT). However, flecainide can also exert pro-arrhythmic effects most notably following myocardial infarction and when used to diagnose Brugada Syndrome (BrS). These divergent actions result from its physiological and pharmacological actions at multiple, interacting, levels of cellular organisation...
April 3, 2017: British Journal of Pharmacology
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