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Prolonged QT syndrome

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https://www.readbyqxmd.com/read/28429460/automated-t-wave-analysis-can-differentiate-acquired-qt-prolongation-from-congenital-long-qt-syndrome
#1
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/28408648/azithromycin-causes-a-novel-proarrhythmic-syndrome
#2
Zhenjiang Yang, Joseph K Prinsen, Kevin R Bersell, Wangzhen Shen, Liudmila Yermalitskaya, Tatiana Sidorova, Paula B Luis, Lynn Hall, Wei Zhang, Liping Du, Ginger Milne, Patrick Tucker, Alfred L George, Courtney M Campbell, Robert A Pickett, Christian M Shaffer, Nagesh Chopra, Tao Yang, Bjorn C Knollmann, Dan M Roden, Katherine T Murray
BACKGROUND: The widely used macrolide antibiotic azithromycin increases risk of cardiovascular and sudden cardiac death, although the underlying mechanisms are unclear. Case reports, including the one we document here, demonstrate that azithromycin can cause rapid, polymorphic ventricular tachycardia in the absence of QT prolongation, indicating a novel proarrhythmic syndrome. We investigated the electrophysiological effects of azithromycin in vivo and in vitro using mice, cardiomyocytes, and human ion channels heterologously expressed in human embryonic kidney (HEK 293) and Chinese hamster ovary (CHO) cells...
April 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28407228/deleterious-protein-altering-mutations-in-the-scn10a-voltage-gated-sodium-channel-gene-are-associated-with-prolonged-qt
#3
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/28394409/evaluation-of-qtc-in-rett-syndrome-correlation-with-age-severity-and-genotype
#4
Jane Crosson, Siddharth Srivastava, Genila M Bibat, Siddharth Gupta, Aditi Kantipuly, Constance Smith-Hicks, Scott M Myers, Abanti Sanyal, Gayane Yenokyan, Joel Brenner, Sakkubai R Naidu
Rett syndrome (RTT) is caused by MECP2 mutations, resulting in various neurological symptoms. Prolonged corrected QT interval (QTc) is also reported and is a speculated cause of sudden death in RTT. The purpose of this study was to correlate QTc in RTT patients with age, clinical severity, and genotype. 100 RTT patients (98 females, 2 males) with MECP2 mutations underwent baseline neurological evaluation (KKI-RTT Severity Scale) and QTc measurement (standard 12 lead electrocardiogram) as part of our prospective natural history study...
April 10, 2017: American Journal of Medical Genetics. Part A
https://www.readbyqxmd.com/read/28382321/electrophysiological-mechanisms-of-long-and-short-qt-syndromes
#5
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/28376710/electrocardiographic-changes-mimicking-acute-coronary-syndrome-in-a-large-intracranial-tumour-a-diagnostic-dilemma
#6
Nilukshana Yogendranathan, H M M T B Herath, S P Pahalagamage, Aruna Kulatunga
BACKGROUND: ST elevation Myocardial infarction is a medical emergency. A variety of noncardiac conditions had been known to mimic the ECG changes that are seen in acute coronary syndrome. Although the common ECG changes that are documented with raised intracranial pressure are T inversions, prolongation of QT interval and sinus bradycardia, ST elevation or depression, arrhythmias and prominent U waves have also been recognized. However, ST elevations in association with primary intracranial tumours are rarely reported...
April 4, 2017: BMC Cardiovascular Disorders
https://www.readbyqxmd.com/read/28371864/a-multicentre-study-of-patients-with-timothy-syndrome
#7
Mark A Walsh, Christian Turner, Katherine W Timothy, Neil Seller, Dominic L Hares, Andrew F James, Jules C Hancox, Orhan Uzun, Dean Boyce, Alan G Stuart, Paul Brennan, Caroline Sarton, Karen McGuire, Ruth A Newbury-Ecob, Karen Mcleod
Aims: Timothy syndrome (TS) is an extremely rare multisystem disorder characterized by marked QT prolongation, syndactyly, seizures, behavioural abnormalities, immunodeficiency, and hypoglycaemia. The aim of this study was to categorize the phenotypes and examine the outcomes of patients with TS. Methods and results: All patients diagnosed with TS in the United Kingdom over a 24-year period were reviewed. Fifteen centres in the British Congenital Arrhythmia Group network were contacted to partake in the study...
March 24, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28369767/multiple-targets-for-flecainide-action-implications-for-cardiac-arrhythmogenesis
#8
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
https://www.readbyqxmd.com/read/28364778/clinical-and-molecular-findings-in-a-moroccan-family-with-jervell-and-lange-nielsen-syndrome-a-case-report
#9
N Adadi, N Lahrouchi, R Bouhouch, I Fellat, R Amri, M Alders, A Sefiani, C Bezzina, I Ratbi
BACKGROUND: Jervell and Lange-Nielsen syndrome (Online Mendelian Inheritance in Man 220400) is a rare autosomal recessive cardioauditory ion channel disorder that affects 1/200,000 to 1/1,000,000 children. It is characterized by congenital profound bilateral sensorineural hearing loss, a long QT interval, ventricular tachyarrhythmias, and episodes of torsade de pointes on an electrocardiogram. Cardiac symptoms arise mostly in early childhood and consist of syncopal episodes during periods of stress, exercise, or fright and are associated with a high risk of sudden cardiac death...
April 2, 2017: Journal of Medical Case Reports
https://www.readbyqxmd.com/read/28356306/effect-of-age-and-sex-on-the-qtc-interval-in-children-and-adolescents-with-type-1-and-2-long-qt-syndrome
#10
Arja S Vink, Sally-Ann B Clur, Ronald B Geskus, Andreas C Blank, Charlotte C A De Kezel, Masao Yoshinaga, Nynke Hofman, Arthur A M Wilde, Nico A Blom
BACKGROUND: In congenital long-QT syndrome, age, sex, and genotype have been associated with cardiac events, but their effect on the trend in QTc interval has never been established. We, therefore, aimed to assess the effect of age and sex on the QTc interval in children and adolescents with type 1 (LQT1) and type 2 (LQT2) long-QT syndrome. METHODS AND RESULTS: QTc intervals of 12-lead resting electrocardiograms were determined, and trends over time were analyzed using a linear mixed-effects model...
April 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28336914/inhibition-of-serum-and-glucocorticoid-regulated-kinase-1-as-novel-therapy-for-cardiac-arrhythmia-disorders
#11
Vassilios J Bezzerides, Aifeng Zhang, Ling Xiao, Bridget Simonson, Santosh A Khedkar, Shiro Baba, Filomena Ottaviano, Stacey Lynch, Katherine Hessler, Alan C Rigby, David Milan, Saumya Das, Anthony Rosenzweig
Alterations in sodium flux (INa) play an important role in the pathogenesis of cardiac arrhythmias and may also contribute to the development of cardiomyopathies. We have recently demonstrated a critical role for the regulation of the voltage-gated sodium channel NaV1.5 in the heart by the serum and glucocorticoid regulated kinase-1 (SGK1). Activation of SGK1 in the heart causes a marked increase in both the peak and late sodium currents leading to prolongation of the action potential duration and an increased propensity to arrhythmia...
March 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28335032/allele-specific-ablation-rescues-electrophysiological-abnormalities-in-a-human-ips-cell-model-of-long-qt-syndrome-with-a-calm2-mutation
#12
Yuta Yamamoto, Takeru Makiyama, Takeshi Harita, Kenichi Sasaki, Yimin Wuriyanghai, Mamoru Hayano, Suguru Nishiuchi, Hirohiko Kohjitani, Sayako Hirose, Jiarong Chen, Fumika Yokoi, Taisuke Ishikawa, Seiko Ohno, Kazuhisa Chonabayashi, Hideki Motomura, Yoshinori Yoshida, Minoru Horie, Naomasa Makita, Takeshi Kimura
Background: Calmodulin is a ubiquitous Ca 2+ sensor molecule encoded by three distinct calmodulin genes, CALM1-3 . Recently, mutations in CALM1-3 have been reported to be associated with severe early-onset long-QT syndrome (LQTS). However, the underlying mechanism through which heterozygous calmodulin mutations lead to severe LQTS remains unknown, particularly in human cardiomyocytes. Objectives: We aimed to establish an LQTS disease model associated with a CALM2 mutation (LQT15) using human induced pluripotent stem cells (hiPSCs) and to assess mutant allele-specific ablation by genome editing for the treatment of LQT15...
March 1, 2017: Human Molecular Genetics
https://www.readbyqxmd.com/read/28323171/acquired-long-qt-syndrome-in-hospitalized-patients
#13
Haixu Yu, Li Zhang, Jinqiu Liu, Ying Liu, Peter R Kowey, Yanli Zhang, Yue Chen, Yushan Wei, Lianjun Gao, Huihua Li, Jie Du, Yunlong Xia
BACKGROUND: Acquired long QT syndrome (ALQTS) has long been overlooked in clinical practice. Recent studies reported that severe ALQTS (QTc ≥500 ms) in hospitalized patients is associated with increased all-cause mortality. OBJECTIVE: We aimed to determine the role of ALQTS in the clinical outcomes of hospitalized patients. METHODS: Electronic medical records were reviewed to identify severe ALQTS in hospitalized patients in a single study center from 9-1-2013 to 2-28-2014...
March 16, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28316956/sudden-infant-death-syndrome-due-to-long-qt-syndrome-a-brief-review-of-the-genetic-substrate-and-prevalence
#14
REVIEW
Nikolaos S Ioakeimidis, Theodora Papamitsou, Soultana Meditskou, Zafiroula Iakovidou-Kritsi
The pathophysiological mechanisms which lead to sudden infant death syndrome (SIDS) are not completely understood. Cardiac channelopathies are a well-established causative factor with long QT syndrome (LQTS) being the most frequent one, accounting for approximately 12% of SIDS cases. The genetic substrate of the above arrhythmogenic syndrome has been thoroughly described but only specific gene mutations or polymorphisms have been identified as SIDS causative. The review will focus on the prevalence of LQTS-induced SIDS or near-SIDS cases and the mutations held responsible...
December 2017: Journal of Biological Research
https://www.readbyqxmd.com/read/28315637/trpm4-non-selective-cation-channel-variants-in-long-qt-syndrome
#15
Thomas Hof, Hui Liu, Laurent Sallé, Jean-Jacques Schott, Corinne Ducreux, Gilles Millat, Philippe Chevalier, Vincent Probst, Romain Guinamard, Patrice Bouvagnet
BACKGROUND: Long QT syndrome (LQTS) is an inherited arrhythmic disorder characterized by prolongation of the QT interval, a risk of syncope, and sudden death. There are already a number of causal genes in LQTS, but not all LQTS patients have an identified mutation, which suggests LQTS unknown genes. METHODS: A cohort of 178 LQTS patients, with no mutations in the 3 major LQTS genes (KCNQ1, KCNH2, and SCN5A), was screened for mutations in the transient potential melastatin 4 gene (TRPM4)...
March 18, 2017: BMC Medical Genetics
https://www.readbyqxmd.com/read/28274542/hypokalemia-in-women-and-methadone-therapy-are-the-strongest-non-cardiologic-factors-associated-with-qt-prolongation-in-an-emergency-department-setting
#16
Keith A Marill, Emily S Miller
BACKGROUND: Our primary objective was to determine the adjusted quantitative associations of clinical predictors with QT prolongation, a defining cause of Torsades de Pointes (TdP). METHODS: A retrospective cohort study was performed on consecutive emergency department patients identified by ECG acquisition date, and heart rate corrected QT (QTc) and QRS durations. QTc was modeled as a function of clinical predictors with multiple linear regression. RESULTS: 1010 patients were included...
February 10, 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/28264985/kcnq1-p-l353l-affects-splicing-and-modifies-the-phenotype-in-a-founder-population-with-long-qt-syndrome-type-1
#17
Jamie D Kapplinger, Anders Erickson, Sirisha Asuri, David J Tester, Sarah McIntosh, Charles R Kerr, Julie Morrison, Anthony Tang, Shubhayan Sanatani, Laura Arbour, Michael J Ackerman
BACKGROUND: Variable expressivity and incomplete penetrance between individuals with identical long QT syndrome (LQTS) causative mutations largely remain unexplained. Founder populations provide a unique opportunity to explore modifying genetic effects. We examined the role of a novel synonymous KCNQ1 p.L353L variant on the splicing of exon 8 and on heart rate corrected QT interval (QTc) in a population known to have a pathogenic LQTS type 1 (LQTS1) causative mutation, p.V205M, in KCNQ1-encoded Kv7...
March 6, 2017: Journal of Medical Genetics
https://www.readbyqxmd.com/read/28249770/long-qt-syndrome-and-left-ventricular-noncompaction-in-4-family-members-across-2-generations-with-kcnq1-mutation
#18
Mira Kharbanda, Amanda Hunter, Stephen Tennant, David Moore, Stephanie Curtis, Jules C Hancox, Victoria Murday
The association of long QT syndrome and left ventricular noncompaction is uncommon, with only a handful of previous reports, and only one reported case in association with a mutation in KCNQ1. Here we present genetic and phenotypic data for 4 family members across 2 generations who all have evidence of prolonged QT interval and left ventricular noncompaction in association with a pathogenic mutation in KCNQ1, and discuss the potential mechanisms of this association. In conclusion, we suggest that it may be helpful to consider looking for mutations in KCNQ1 in similar patients...
February 27, 2017: European Journal of Medical Genetics
https://www.readbyqxmd.com/read/28235848/patients-with-long-qt-syndrome-due-to-impaired-herg-encoded-kv11-1-potassium-channel-have-exaggerated-endocrine-pancreatic-and-incretin-function-associated-with-reactive-hypoglycemia
#19
Louise Hyltén-Cavallius, Eva W Iepsen, Nicolai J Wewer Albrechtsen, Mathilde Svendstrup, Anniek F Lubberding, Bolette Hartmann, Thomas Jespersen, Allan Linneberg, Michael Christiansen, Henrik Vestergaard, Oluf Pedersen, Jens J Holst, Jørgen K Kanters, Torben Hansen, Signe S Torekov
Background -Loss-of-function mutations in hERG (encoding the Kv11.1 voltage-gated potassium channel) cause long QT syndrome (LQT2) due to prolonged cardiac repolarization. However, Kv11.1 is also present in pancreatic α and β cells and intestinal L and K cells, secreting glucagon, insulin, and the incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), respectively. These hormones are crucial for glucose regulation and LQTS may cause disturbed glucose regulation. We measured secretion of these hormones and cardiac repolarization in response to glucose ingestion in LQT2 patients with functional mutations in hERG and matched healthy participants, testing the hypothesis that LQT2 patients have increased incretin and β cell- and decreased α cell function and thus lower glucose levels...
February 24, 2017: Circulation
https://www.readbyqxmd.com/read/28213505/revealing-the-concealed-nature-of-long-qt-type-3-syndrome
#20
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
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