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Long qt syndrome

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https://www.readbyqxmd.com/read/29046645/computational-cardiac-modeling-reveals-mechanisms-of-ventricular-arrhythmogenesis-in-long-qt-syndrome-type-8-cacna1c-r858h-mutation-linked-to-ventricular-fibrillation
#1
Jieyun Bai, Kuanquan Wang, Yashu Liu, Yacong Li, Cuiping Liang, Gongning Luo, Suyu Dong, Yongfeng Yuan, Henggui Zhang
Functional analysis of the L-type calcium channel has shown that the CACNA1C R858H mutation associated with severe QT interval prolongation may lead to ventricular fibrillation (VF). This study investigated multiple potential mechanisms by which the CACNA1C R858H mutation facilitates and perpetuates VF. The Ten Tusscher-Panfilov (TP06) human ventricular cell models incorporating the experimental data on the kinetic properties of L-type calcium channels were integrated into one-dimensional (1D) fiber, 2D sheet, and 3D ventricular models to investigate the pro-arrhythmic effects of CACNA1C mutations by quantifying changes in intracellular calcium handling, action potential profiles, action potential duration restitution (APDR) curves, dispersion of repolarization (DOR), QT interval and spiral wave dynamics...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/29042423/low-prevalence-of-inappropriate-shocks-in-patients-with-inherited-arrhythmia-syndromes-with-the-subcutaneous-implantable-defibrillator-single-center-experience-and-long-term-follow-up
#2
Boris Rudic, Erol Tülümen, Veronika Berlin, Susanne Röger, Ksenija Stach, Volker Liebe, Ibrahim El-Battrawy, Christina Dösch, Theano Papavassiliu, Ibrahim Akin, Martin Borggrefe, Jürgen Kuschyk
BACKGROUND: Up to 40% of patients with transvenous implantable cardioverter-defibrillator (ICD) experience lead-associated complications and may suffer from high complication rates when lead extraction is indicated. Subcutaneous ICD may represent a feasible alternative; however, the efficacy of the subcutaneous ICD in the detection and treatment of ventricular arrhythmias in patients with hereditary arrhythmia syndromes has not been fully evaluated. METHODS AND RESULTS: Patients with primary hereditary arrhythmia syndromes who fulfilled indication for defibrillator placement were eligible for enrollment...
October 17, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/29040441/advancing-precision-medicine-for-the-treatment-of-long-qt-syndrome-type-2-shedding-light-on-lumacaftor
#3
Brian P Delisle, Craig T January
No abstract text is available yet for this article.
October 11, 2017: European Heart Journal
https://www.readbyqxmd.com/read/29037160/-homozygous-and-compound-heterozygous-mutation-in-3-turkish-family-with-jervell-and-lange-nielsen-syndrome-case-reports
#4
Fahrettin Uysal, Burcu Turkgenc, Guven Toksoy, Ozlem M Bostan, Elif Evke, Oya Uyguner, Cengiz Yakicier, Hulya Kayserili, Ergun Cil, Sehime G Temel
BACKGROUND: Jervell and Lange-Nielsen syndrome (JLNS) isa recessive model of long QT syndrome which might also be related to possible hearing loss. Although the syndrome has been demonstrated to be originated from homozygous or compound heterozygous mutations in either the KCNQ1 or KCNE1 genes, additional mutations in other genetic loci should be considered, particularly in malignant course patients. CASE PRESENTATIONS: Three patients were admitted into hospital due to recurrent seizures/syncope, intrauterine and postnatal bradycardia respectively; moreover all three patients had congenital sensorineural hearing-loss...
October 16, 2017: BMC Medical Genetics
https://www.readbyqxmd.com/read/29036559/the-brisk-standing-test-for-long-qt-syndrome-in-prepubertal-school-children-defining-normal
#5
L H P M Filippini, P G Postema, K Zoubin, B J M Hermans, N A Blom, T Delhaas, A A M Wilde
Aims: Long QT syndrome (LQTS) is associated with malignant arrhythmias and sudden death from birth to advanced age. Prolongation of the QT-interval, may however be concealed on standard electrocardiograms (ECG). The brisk-standing-test (BST) was developed to guide LQTS-diagnosis and treatment in adults. We hypothesized that the BST may be used in prepubertal children to identify LQTS subjects. Accordingly, reference values for the BST should be available to prevent incorrect diagnosis and treatment of LQTS...
October 3, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/29036457/feasibility-evaluation-of-long-term-use-of-beta-blockers-and-calcium-antagonists-in-patients-with-brugada-syndrome
#6
Tsukasa Kamakura, Mitsuru Wada, Kohei Ishibashi, Yuko Y Inoue, Koji Miyamoto, Hideo Okamura, Satoshi Nagase, Takashi Noda, Takeshi Aiba, Satoshi Yasuda, Wataru Shimizu, Shiro Kamakura, Kengo Kusano
Aims: Beta-blockers (BBs) and calcium antagonists (CAs) are reported to aggravate ST-segment elevation in some patients with Brugada syndrome (BrS). The feasibility of their long-term use in BrS still remains unknown. We investigated the safety of long-term use of BB and CA in BrS patients. Methods and results: Of the 360 consecutive BrS patients, 29 [5: a history of ventricular fibrillation (VF), 17: syncope, 7: asymptomatic] took BB and/or CA (BB: 22, CA: 8) for more than 1 year for the treatment of co-morbidities such as atrial tachyarrhythmia, vasospastic angina, and neurally mediated syncope...
September 23, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/29033053/identification-and-characterization-of-a-novel-recessive-kcnq1-mutation-associated-with-romano-ward-long-qt-syndrome-in-two-iranian-families
#7
Zahra Zafari, Mohammad Dalili, Sirus Zeinali, Siamak Saber, Amir Farjam Fazeli Far, Mohammad Taghi Akbari
BACKGROUND: One of the foremost causes of sudden cardiac death in the young is an inherent cardiac arrhythmia known as Long-QT syndrome (LQTS). Whereas heterozygous mutations typically lead to the Romano-Ward type of LQTS, We have provided a further evidence for the recessive transmission of a novel KCNQ1 gene mutation in two consanguineous families for the first time in Iran. METHODS: Next generation sequencing, DNA Sanger sequencing and haplotype analysis were performed for genotype determination...
July 12, 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/29032483/regulation-of-cardiac-voltage-gated-sodium-channel-by-kinases-roles-of-protein-kinases-a-and-c
#8
Ademuyiwa S Aromolaran, Mohamed Chahine, Mohamed Boutjdir
In the heart, voltage-gated sodium (Nav) channel (Nav1.5) is defined by its pore-forming α-subunit and its auxiliary β-subunits, both of which are important for its critical contribution to the initiation and maintenance of the cardiac action potential (AP) that underlie normal heart rhythm. The physiological relevance of Nav1.5 is further marked by the fact that inherited or congenital mutations in Nav1.5 channel gene SCN5A lead to altered functional expression (including expression, trafficking, and current density), and are generally manifested in the form of distinct cardiac arrhythmic events, epilepsy, neuropathic pain, migraine, and neuromuscular disorders...
October 15, 2017: Handbook of Experimental Pharmacology
https://www.readbyqxmd.com/read/29021868/management-of-patients-with-long-qt-syndrome
#9
Serkan Cay, Ozcan Ozeke, Firat Ozcan, Serhat Koca, Aysenur Pac, Dursun Aras, Serkan Topaloglu
No abstract text is available yet for this article.
October 2017: Journal of Arrhythmia
https://www.readbyqxmd.com/read/29021858/landiolol-suppression-of-electrical-storm-of-torsades-de-pointes-in-patients-with-congenital-long-qt-syndrome-type-2-and-myocardial-ischemia
#10
Ryota Kitajima, Takeshi Aiba, Tsukasa Kamakura, Kohei Ishibashi, Mitsuru Wada, Yuko Inoue, Koji Miyamoto, Hideo Okamura, Takashi Noda, Satoshi Nagase, Yu Kataoka, Yasuhide Asaumi, Teruo Noguchi, Satoshi Yasuda, Kengo Kusano
A 76-year-old man who had been diagnosed with long-QT syndrome type 2 had frequent syncopal attacks. The electrocardiogram was monitored, and frequent torsades de pointes (TdP) was detected despite administration of conventional medications: oral propranolol, verapamil, intravenous magnesium sulfate, verapamil, and lidocaine. In contrast, 2 μg/kg/min landiolol could completely suppress TdP. Subsequently, an implantable cardioverter defibrillator was placed, and he was diagnosed with silent myocardial ischemia using myocardial perfusion scintigraphy and coronary angiography...
October 2017: Journal of Arrhythmia
https://www.readbyqxmd.com/read/29021308/machine-learning-and-rare-variant-adjudication-in-type-1-long-qt-syndrome
#11
EDITORIAL
John R Giudicessi
No abstract text is available yet for this article.
October 2017: Circulation. Cardiovascular Genetics
https://www.readbyqxmd.com/read/29021306/characterization-of-a-human-induced-pluripotent-stem-cell-derived-cardiomyocyte-model-for-the-study-of-variant-pathogenicity-validation-of-a-kcnj2-mutation
#12
Roselle Gélinas, Nabil El Khoury, Marie-A Chaix, Claudine Beauchamp, Azadeh Alikashani, Nathalie Ethier, Gabrielle Boucher, Louis Villeneuve, Laura Robb, Frédéric Latour, Blandine Mondesert, Lena Rivard, Philippe Goyette, Mario Talajic, Céline Fiset, John David Rioux
BACKGROUND: Long-QT syndrome is a potentially fatal condition for which 30% of patients are without a genetically confirmed diagnosis. Rapid identification of causal mutations is thus a priority to avoid at-risk situations that can lead to fatal cardiac events. Massively parallel sequencing technologies are useful for the identification of sequence variants; however, electrophysiological testing of newly identified variants is crucial to demonstrate causality. Long-QT syndrome could, therefore, benefit from having a standardized platform for functional characterization of candidate variants in the physiological context of human cardiomyocytes...
October 2017: Circulation. Cardiovascular Genetics
https://www.readbyqxmd.com/read/29021305/predicting-the-functional-impact-of-kcnq1-variants-of-unknown-significance
#13
Bian Li, Jeffrey L Mendenhall, Brett M Kroncke, Keenan C Taylor, Hui Huang, Derek K Smith, Carlos G Vanoye, Jeffrey D Blume, Alfred L George, Charles R Sanders, Jens Meiler
BACKGROUND: An emerging standard-of-care for long-QT syndrome uses clinical genetic testing to identify genetic variants of the KCNQ1 potassium channel. However, interpreting results from genetic testing is confounded by the presence of variants of unknown significance for which there is inadequate evidence of pathogenicity. METHODS AND RESULTS: In this study, we curated from the literature a high-quality set of 107 functionally characterized KCNQ1 variants. Based on this data set, we completed a detailed quantitative analysis on the sequence conservation patterns of subdomains of KCNQ1 and the distribution of pathogenic variants therein...
October 2017: Circulation. Cardiovascular Genetics
https://www.readbyqxmd.com/read/29020304/identification-of-a-targeted-and-testable-antiarrhythmic-therapy-for-long-qt-syndrome-type-2-using-a-patient-specific-cellular-model
#14
Ashish Mehta, Chrishan J A Ramachandra, Pritpal Singh, Anuja Chitre, Chong Hui Lua, Manuela Mura, Lia Crotti, Philip Wong, Peter J Schwartz, Massimiliano Gnecchi, Winston Shim
Aims: Loss-of-function mutations in the hERG gene causes long-QT syndrome type 2 (LQT2), a condition associated with reduced IKr current. Four different mutation classes define the molecular mechanisms impairing hERG. Among them, Class 2 mutations determine hERG trafficking defects. Lumacaftor (LUM) is a drug acting on channel trafficking already successfully tested for cystic fibrosis and its safety profile is well known. We hypothesize that LUM might rescue also hERG trafficking defects in LQT2 and exert anti-arrhythmic effects...
July 21, 2017: European Heart Journal
https://www.readbyqxmd.com/read/29020060/phosphatidylinositol-4-5-bisphosphate-is-required-for-kcnq1-kcne1-channel-function-but-not-anterograde-trafficking
#15
Alice A Royal, Andrew Tinker, Stephen C Harmer
The slow delayed-rectifier potassium current (IKs) is crucial for human cardiac action potential repolarization. The formation of IKs requires co-assembly of the KCNQ1 α-subunit and KCNE1 β-subunit, and mutations in either of these subunits can lead to hereditary long QT syndrome types 1 and 5, respectively. It is widely recognised that the KCNQ1/KCNE1 (Q1/E1) channel requires phosphatidylinositol-4,5-bisphosphate (PIP2) binding for function. We previously identified a cluster of basic residues in the proximal C-terminus of KCNQ1 that form a PIP2/phosphoinositide binding site...
2017: PloS One
https://www.readbyqxmd.com/read/29017927/eleclazine-exhibits-enhanced-selectivity-for-lqt3-associated-late-ina
#16
Nesrine El-Bizri, Cheng Xie, Lynda Liu, James Limberis, Michael Krause, Ryoko Hirakawa, Steven Nguyen, Dennis R Tabuena, Luiz Belardinelli, Kristopher M Kahlig
BACKGROUND: Eleclazine (GS-6615) is a sodium channel blocker designed to improve the selectivity for cardiac late INa over peak INa. OBJECTIVE: This study investigates the inhibition of late INa by eleclazine using a sample of Long QT type-3 (LQT3) and overlap LQT3/Brugada syndrome (LQT3/BS) mutant channels. The apparent binding rates for eleclazine were compared to other class 1 antiarrhythmics and the binding site was investigated. METHODS: Wild-type hNaV1...
October 7, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/29016797/multiple-clinical-profiles-of-families-with-the-short-qt-syndrome
#17
D Akdis, A M Saguner, A Medeiros-Domingo, A Schaller, C Balmer, J Steffel, C Brunckhorst, F Duru
Aims: Short QT syndrome (SQTS) is a rare cardiac channelopathy characterized by a shortened corrected QT (QTc)-interval that can lead to ventricular arrhythmias and sudden cardiac death. The aim of this study was to investigate the clinical phenotypes and long-term outcomes of three families harbouring genetic mutations associated with the SQTS. Methods and results: Clinical data included medical history, physical examination, 12-lead ECG, 24-h Holter-ECG, and transthoracic echocardiography from three index patients and their first-degree relatives...
July 19, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/29016765/broad-antiarrhythmic-effect-of-mexiletine-in-different-arrhythmia-models
#18
Gerrit Frommeyer, Jonas Garthmann, Christian Ellermann, Dirk G Dechering, Simon Kochhäuser, Florian Reinke, Julia Köbe, Kristina Wasmer, Lars Eckardt
Aims: Experimental studies and clinical reports suggest antiarrhythmic properties of mexiletine in different arrhythmias. We aimed at investigating mexiletine in experimental models of atrial fibrillation (AF) as well as in long-QT- (LQTS) and short-QT-syndrome (SQTS). Methods and results: In 15 isolated rabbit hearts, erythromycin (300 µM) was infused for simulation of long-QT-2-syndrome. In further 13 hearts, veratridine was administered to simulate long-QT-3-syndrome...
August 1, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28992755/drug-mediated-shortening-of-action-potentials-in-lqts2-human-induced-pluripotent-stem-cell-derived-cardiomyocytes
#19
Gary Duncan, Karl Firth, Vinoj George, Minh Duc Hoang, Andrew Staniforth, Godfrey Smith, Chris Denning
Cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSCs) are now a well-established modality for modelling genetic disorders of the heart. This is especially so for long QT syndrome (LQTS), which is caused by perturbation of ion channel function, and can lead to fainting, malignant arrhythmias and sudden cardiac death. LQTS2 is caused by mutations in KCNH2, a gene whose protein product contributes to IKr (also known as HERG), which is the predominant repolarising potassium current in CMs...
October 9, 2017: Stem Cells and Development
https://www.readbyqxmd.com/read/28992529/a-comprehensive-structural-model-for-the-human-kcnq1-kcne1-ion-channel
#20
Horia Jalily Hasani, Marawan Ahmed, Khaled Barakat
The voltage-gated KCNQ1/KCNE1 potassium ion channel complex, forms the slow delayed rectifier (IKs) current in the heart, which plays an important role in heart signaling. The importance of KCNQ1/KCNE1 channel's function is further implicated by the linkage between loss-of-function and gain-of-function mutations in KCNQ1 or KCNE1, and long QT syndromes, congenital atrial fibrillation, and short QT syndrome. Also, KCNQ1/KCNE1 channels are an off-target for many non-cardiovascular drugs, leading to fatal cardiac irregularities...
September 29, 2017: Journal of Molecular Graphics & Modelling
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