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https://www.readbyqxmd.com/read/30036649/genotype-and-clinical-characteristics-of-congenital-long-qt-syndrome-in-thailand
#1
Ankavipar Saprungruang, Apichai Khongphatthanayothin, John Mauleekoonphairoj, Pharawee Wandee, Supaluck Kanjanauthai, Zahurul A Bhuiyan, Arthur A M Wilde, Yong Poovorawan
BACKGROUND: Congenital long QT syndrome (LQTS) is an inheritable arrhythmic disorder which is linked to at least 17 genes. The clinical characteristics and genetic mutations may be variable among different population groups and they have not yet been studied in Thai population. METHODS: Clinical characteristics were retrospectively reviewed from children and young adults with congenital long QT syndrome whose blood samples were sent for genotyping during 1998-2017...
July 20, 2018: Indian Pacing and Electrophysiology Journal
https://www.readbyqxmd.com/read/29983085/mexiletine-rescues-a-mixed-biophysical-phenotype-of-the-cardiac-sodium-channel-arising-from-the-scn5a-mutation-n406k-found-in-lqt3-patients
#2
Rou-Mu Hu, David J Tester, Ryan Li, Tianyu Sun, Blaise Z Peterson, Michael J Ackerman, Jonathan C Makielski, Bi-Hua Tan
INTRODUCTION: Individual mutations in the SCN5A-encoding cardiac sodium channel α-subunit usually cause a single cardiac arrhythmia disorder, some cause mixed biophysical or clinical phenotypes. Here we report an infant, female patient harboring a N406K mutation in SCN5A with a marked and mixed biophysical phenotype and assess pathogenic mechanisms. METHODS AND RESULTS: A patient suffered from recurrent seizures during sleep and torsades de pointes with a QTc of 530 ms...
2018: Channels
https://www.readbyqxmd.com/read/29791480/complex-interactions-in-a-novel-scn5a-compound-mutation-associated-with-long-qt-and-brugada-syndrome-implications-for-na-channel-blocking-pharmacotherapy-for-de-novo-conduction-disease
#3
Jie Liu, Jason D Bayer, Roozbeh Aschar-Sobbi, Marianne Wauchop, Danna Spears, Michael Gollob, Edward J Vigmond, Robert Tsushima, Peter H Backx, Vijay S Chauhan
BACKGROUND: The SCN5A mutation, P1332L, is linked to a malignant form of congenital long QT syndrome, type 3 (LQT3), and affected patients are highly responsive to the Na+ channel blocking drug, mexiletine. In contrast, A647D is an atypical SCN5A mutation causing Brugada syndrome. An asymptomatic male with both P1332L and A647D presented with varying P wave/QRS aberrancy and mild QTc prolongation which did not shorten measurably with mexiletine. OBJECTIVE: We characterized the biophysical properties of P1332L, A647D and wild-type (WT) Na+ channels as well as their combinations in order to understand our proband's phenotype and to guide mexilitine therapy...
2018: PloS One
https://www.readbyqxmd.com/read/29754923/enhanced-late-sodium-current-underlies-pro-arrhythmic-intracellular-sodium-and-calcium-dysregulation-in-murine-sodium-channelopathy
#4
Mathilde R Rivaud, Antonius Baartscheer, Arie O Verkerk, Leander Beekman, Sridharan Rajamani, Luiz Belardinelli, Connie R Bezzina, Carol Ann Remme
BACKGROUND: Long QT syndrome mutations in the SCN5A gene are associated with an enhanced late sodium current (INa,L ) which may lead to pro-arrhythmic action potential prolongation and intracellular calcium dysregulation. We here investigated the dynamic relation between INa,L , intracellular sodium ([Na+ ]i ) and calcium ([Ca2+ ]i ) homeostasis and pro-arrhythmic events in the setting of a SCN5A mutation. METHODS AND RESULTS: Wild-type (WT) and Scn5a1798insD/+ (MUT) mice (age 3-5 months) carrying the murine homolog of the SCN5A-1795insD mutation on two distinct genetic backgrounds (FVB/N and 129P2) were studied...
July 15, 2018: International Journal of Cardiology
https://www.readbyqxmd.com/read/29723683/beyond-the-length-and-look-of-repolarization-defining-the-non-qtc-electrocardiographic-profiles-of-patients-with-congenital-long-qt-syndrome
#5
Conor M Lane, J Martijn Bos, Ram K Rohatgi, Michael J Ackerman
BACKGROUND: Little is known about the spectrum and prevalence of ECG features beyond the length and morphology of repolarization in patients with congenital long QT syndrome (LQTS). OBJECTIVE: The purpose of this study was to characterize the full ECG phenotype of LQTS patients and evaluate differences by age and LQTS genotype. METHODS: Retrospective review of 943 patients with LQTS (57% female; median age 25 years; interquartile range 9-34 years) was performed...
April 30, 2018: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/29650123/interplay-between-genetic-substrate-qtc-duration-and-arrhythmia-risk-in-patients-with-long-qt-syndrome
#6
Andrea Mazzanti, Riccardo Maragna, Gaetano Vacanti, Nicola Monteforte, Raffaella Bloise, Maira Marino, Lorenzo Braghieri, Patrick Gambelli, Mirella Memmi, Eleonora Pagan, Massimo Morini, Alberto Malovini, Martin Ortiz, Luciana Sacilotto, Riccardo Bellazzi, Lorenzo Monserrat, Carlo Napolitano, Vincenzo Bagnardi, Silvia G Priori
BACKGROUND: Long QT syndrome (LQTS) is a common inheritable arrhythmogenic disorder, often secondary to mutations in the KCNQ1, KCNH2, and SCN5A genes. The disease is characterized by a prolonged ventricular repolarization (QTc interval) that confers susceptibility to life-threatening arrhythmic events (LAEs). OBJECTIVES: This study sought to create an evidence-based risk stratification scheme to personalize the quantification of the arrhythmic risk in patients with LQTS...
April 17, 2018: Journal of the American College of Cardiology
https://www.readbyqxmd.com/read/29504689/clinical-aspects-of-the-three-major-genetic-forms-of-long-qt-syndrome-lqt1-lqt2-lqt3
#7
Valentina Kutyifa, Usama A Daimee, Scott McNitt, Bronislava Polonsky, Charles Lowenstein, Kris Cutter, Coeli Lopes, Wojciech Zareba, Arthur J Moss
BACKGROUND: A comprehensive report on the clinical course of the three major genotypes of the long QT syndrome (LQTS) in a large U.S. patient cohort is lacking. METHODS: Our study consisted of 1,923 U.S. subjects from the Rochester-based LQTS Registry with genotype-positive LQT1 (n = 879), LQT2 (n = 807), and LQT3 (n = 237). We evaluated the risk of a first cardiac event (syncope, aborted cardiac arrest, or sudden cardiac death, whichever occurred first) from birth through age 50 years...
May 2018: Annals of Noninvasive Electrocardiology
https://www.readbyqxmd.com/read/29483621/the-efficacy-of-ranolazine-on-e1784k-is-altered-by-temperature-and-calcium
#8
Mena Abdelsayed, Manpreet Ruprai, Peter C Ruben
E1784K is the most common mixed syndrome SCN5a mutation underpinning both Brugada syndrome type 1 (BrS1) and Long-QT syndrome type 3 (LQT3). The charge reversal mutant enhances the late sodium current (INa ) passed by the cardiac voltage-gated sodium channel (NaV 1.5), delaying cardiac repolarization. Exercise-induced triggers, like elevated temperature and cytosolic calcium, exacerbate E1784K late INa . In this study, we tested the effects of Ranolazine, the late INa blocker, on voltage-dependent and kinetic properties of E1784K at elevated temperature and cytosolic calcium...
February 26, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29101013/the-congenital-long-qt-syndrome-type-3-an-update
#9
REVIEW
Andrés Ricardo Pérez-Riera, Raimundo Barbosa-Barros, Rodrigo Daminello Raimundo, Marianne Penachini da Costa de Rezende Barbosa, Isabel Cristina Esposito Sorpreso, Luiz Carlos de Abreu
Congenital long QT syndrome type 3 (LQT3) is the third in frequency compared to the 15 forms known currently of congenital long QT syndrome (LQTS). Cardiac events are less frequent in LQT3 when compared with LQT1 and LQT2, but more likely to be lethal; the likelihood of dying during a cardiac event is 20% in families with an LQT3 mutation and 4% with either an LQT1 or an LQT2 mutation. LQT3 is consequence of mutation of gene SCN5A which codes for the Nav1.5 Na+ channel α-subunit and electrocardiographically characterized by a tendency to bradycardia related to age, prolonged QT/QTc interval (mean QTc value 478 ± 52 ms), accentuated QT dispersion consequence of prolonged ST segment, late onset of T wave and frequent prominent U wave because of longer repolarization of the M cell across left ventricular wall...
January 2018: Indian Pacing and Electrophysiology Journal
https://www.readbyqxmd.com/read/29059199/effectiveness-of-beta-blockers-depending-on-the-genotype-of-congenital-long-qt-syndrome-a-meta-analysis
#10
Jinhee Ahn, Hyun Jung Kim, Jong-Il Choi, Kwang No Lee, Jaemin Shim, Hyeong Sik Ahn, Young-Hoon Kim
BACKGROUND: Beta-blockers are first-line therapy in patients with congenital long-QT syndrome (LQTS). OBJECTIVE: This study sought to determine the differences in effectiveness of beta-blockers on risk reduction according to LQTS genotype. METHODS: We searched MEDLINE, EMBASE, and CENTRAL databases to investigate the use of beta-blockers (atenolol, nadolol, propranolol, and metoprolol) in patients with LQTS. Hazard ratio (HR) and relative risk (RR) were extracted or calculated from studies reporting cardiac events (syncope, aborted cardiac arrest (ACA), or sudden cardiac death (SCD))...
2017: PloS One
https://www.readbyqxmd.com/read/29017927/eleclazine-exhibits-enhanced-selectivity-for-long-qt-syndrome-type-3-associated-late-na-current
#11
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 Na+ current (INa ) over peak INa . OBJECTIVES: The goals of this study were to investigate the inhibition of late INa by eleclazine using a sample of long QT syndrome type 3 (LQT3) and overlap LQT3/Brugada syndrome mutant channels; to compare the apparent binding rates for eleclazine with those for other class 1 antiarrhythmic agents; and to investigate the binding site...
February 2018: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28942950/jt-interval-what-does-this-interval-mean
#12
Wojciech Zareba, Scott McNitt, Slava Polonsky, Jean-Philippe Couderc
The JTp interval gained interest as a marker differentiating effects of drugs on cardiac ion channels. For JTp interval, both the beginning - identification of J point and identification of T wave end remains the subject of substantial variability. We aimed to analyze diagnostic and prognostic performance of JTp interval in the International LQTS Registry data. ECGs from 804 gene carriers and 1139 non-carriers from LQT1 families, 735 carriers and 1145 non-carriers from LQT2 families, and 238 carriers and 554 non-carriers from LQT3 families were evaluated...
November 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/28756098/phenotypic-variability-in-lqt3-human-induced-pluripotent-stem-cell-derived-cardiomyocytes-and-their-response-to-antiarrhythmic-pharmacologic-therapy-an-in-silico-approach
#13
Michelangelo Paci, Elisa Passini, Stefano Severi, Jari Hyttinen, Blanca Rodriguez
BACKGROUND: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are in vitro models with the clear advantages of their human origin and suitability for human disease investigations. However, limitations include their incomplete characterization and variability reported in different cell lines and laboratories. OBJECTIVE: The purpose of this study was to investigate in silico ionic mechanisms potentially explaining the phenotypic variability of hiPSC-CMs in long QT syndrome type 3 (LQT3) and their response to antiarrhythmic drugs...
November 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28728690/contemporary-outcomes-in-patients-with%C3%A2-long-qt-syndrome
#14
Ram K Rohatgi, Alan Sugrue, J Martijn Bos, Bryan C Cannon, Samuel J Asirvatham, Christopher Moir, Heidi J Owen, Katy M Bos, Teresa Kruisselbrink, Michael J Ackerman
BACKGROUND: Long QT syndrome (LQTS) is a potentially lethal cardiac channelopathy with a 1% to 5% annual risk of LQTS-triggered syncope, aborted cardiac arrest, or sudden cardiac death. OBJECTIVES: This study sought to evaluate LQTS outcomes from a single center in the contemporary era. METHODS: The authors conducted a retrospective study comprising the 606 patients with LQTS (LQT1 in 47%, LQT2 in 34%, and LQT3 in 9%) who were evaluated in Mayo Clinic's Genetic Heart Rhythm Clinic from January 1999 to December 2015...
July 25, 2017: Journal of the American College of Cardiology
https://www.readbyqxmd.com/read/28416468/cardiac-transplantation-in-children-and-adolescents-with-long-qt-syndrome
#15
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: The purpose of this study was to evaluate the incidence of and risk factors for cardiac transplantation in 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...
August 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28412158/lidocaine-attenuation-testing-an-in-vivo-investigation-of-putative-lqt3-associated-variants-in-the-scn5a-encoded-sodium-channel
#16
Heather N Anderson, J Martijn Bos, Jamie D Kapplinger, Jana M Meskill, Dan Ye, Michael J Ackerman
BACKGROUND: Long QT syndrome type 3 (LQT3) accounts for 5%-10% of long QT syndrome and results from gain-of-function mutations in the SCN5A-encoded sodium channel. Approximately 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: The purpose of this study was to assess the use of the lidocaine attenuation test (LAT) in evaluating patients with possible LQT3...
August 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28339995/long-term-flecainide-therapy-in-type-3-long-qt-syndrome
#17
Ehud Chorin, Rivki Taub, Aron Medina, Nir Flint, Sami Viskin, Jesaia Benhorin
Aims: Type 3 long QT syndrome (LQT3) is caused by gain-of-function mutations in the cardiac sodium channel gene (SCN5A). Previous reports on the long-term use of sodium channel blockers in LQT3 are sparse. The objective of the current study was to evaluate the long-term safety and efficacy of flecainide therapy in patients with LQT3 who carry the D1790G SCN5A mutation. Methods and results: The study population comprised 30 D1790G carriers who were treated with flecainide and followed for 1-215 months (mean 145 ± 54 months, median 140 months)...
February 1, 2018: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28292826/arrhythmia-risk-and-%C3%AE-blocker-therapy-in-pregnant-women-with-long-qt-syndrome
#18
Kohei Ishibashi, Takeshi Aiba, Chizuko Kamiya, Aya Miyazaki, Heima Sakaguchi, Mitsuru Wada, Ikutaro Nakajima, Koji Miyamoto, Hideo Okamura, Takashi Noda, Toshifumi Yamauchi, Hideki Itoh, Seiko Ohno, Hideki Motomura, Yoshiharu Ogawa, Hiroko Goto, Takaomi Minami, Nobue Yagihara, Hiroshi Watanabe, Kanae Hasegawa, Akihiro Terasawa, Hitoshi Mikami, Kayo Ogino, Yukiko Nakano, Sato Imashiro, Yosuke Fukushima, Yoshimitsu Tsuzuki, Koko Asakura, Jun Yoshimatsu, Isao Shiraishi, Shiro Kamakura, Yoshihiro Miyamoto, Satoshi Yasuda, Takashi Akasaka, Minoru Horie, Wataru Shimizu, Kengo Kusano
BACKGROUND: Pregnancy is one of the biggest concerns for women with long QT syndrome (LQTS). OBJECTIVES: This study investigated pregnancy-related arrhythmic risk and the efficacy and safety of β-blocker therapy for lethal ventricular arrhythmias in pregnant women with LQTS (LQT-P) and their babies. METHODS: 136 pregnancies in 76 LQT-P (29±5 years old; 22 LQT1, 36 LQT2, one LQT3, and 17 genotype-unknown) were enrolled. We retrospectively analysed their clinical and electrophysiological characteristics and pregnancy outcomes in the presence (BB group: n=42) or absence of β-blocker therapy (non-BB group: n=94)...
September 2017: Heart: Official Journal of the British Cardiac Society
https://www.readbyqxmd.com/read/28213505/revealing-the-concealed-nature-of-long-qt-type-3-syndrome
#19
Amara Greer-Short, Sharon A George, Steven Poelzing, Seth H Weinberg
BACKGROUND: Gain-of-function mutations in the voltage-gated sodium channel (Nav1.5) are associated with the long-QT-3 (LQT3) syndrome. Nav1.5 is densely expressed at the intercalated disk, and narrow intercellular separation can modulate cell-to-cell coupling via extracellular electric fields and depletion of local sodium ion nanodomains. Models predict that significantly decreasing intercellular cleft widths slows conduction because of reduced sodium current driving force, termed "self-attenuation...
February 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28118183/fatal-ventricular-arrhythmias-in-a-young-male-with-unrecognized-lqt3-and-cardiolaminopathy
#20
Anna Piccoli, Lorenzo Giuliani, Eloisa Arbustini
No abstract text is available yet for this article.
January 2017: Journal of Cardiovascular Medicine
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