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Prolonged QT syndrome

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https://www.readbyqxmd.com/read/28632743/in-silico-assessment-of-the-effects-of-quinidine-disopyramide-and-e-4031-on-short-qt-syndrome-variant-1-in-the-human-ventricles
#1
Cunjin Luo, Kuanquan Wang, Henggui Zhang
AIMS: Short QT syndrome (SQTS) is an inherited disorder associated with abnormally abbreviated QT intervals and an increased incidence of atrial and ventricular arrhythmias. SQT1 variant (linked to the rapid delayed rectifier potassium channel current, IKr) of SQTS, results from an inactivation-attenuated, gain-of-function mutation (N588K) in the KCNH2-encoded potassium channels. Pro-arrhythmogenic effects of SQT1 have been well characterized, but less is known about the possible pharmacological antiarrhythmic treatment of SQT1...
2017: PloS One
https://www.readbyqxmd.com/read/28619993/low-extracellular-potassium-prolongs-repolarization-and-evokes-early-afterdepolarization-in-human-induced-pluripotent-stem-cell-derived-cardiomyocytes
#2
Jukka Kuusela, Kim Larsson, Disheet Shah, Chandra Prajapati, Katriina Aalto-Setälä
Long QT syndrome (LQTS) is characterized by a prolonged QT-interval on electrocardiogram and by increased risk of sudden death. One of the most common and potentially life-threatening electrolyte disturbances is hypokalemia, characterized by low concentrations of K(+) Using a multielectrode array platform and current clamp technique, we investigated the effect of low extracellular K(+) concentration ([K(+)]Ex) on the electrophysiological properties of hiPSC-derived cardiomyocytes (CMs) generated from a healthy control subject (WT) and from two symptomatic patients with type 1 of LQTS carrying G589D (LQT1A) or IVS7-2A>G mutation (LQT1B) in KCNQ1 The baseline prolongations of field potential durations (FPDs) and action potential durations (APDs) were longer in LQT1-CMs than in WT-CMs...
June 15, 2017: Biology Open
https://www.readbyqxmd.com/read/28616803/amitriptyline-may-have-possibility-to-induce-brugada-syndrome-rather-than-long-qt-syndrome
#3
Nur Jaharat Lubna, Takeshi Wada, Yuji Nakamura, Koki Chiba, Xin Cao, Hiroko Izumi-Nakaseko, Kentaro Ando, Atsuhiko T Naito, Yoshioki Satoh, Atsushi Sugiyama
Amitriptyline has been reported to induce long QT syndrome in addition to Brugada syndrome. We qualitatively and quantitatively analyzed the potential of amitriptyline to induce these lethal syndromes by using the halothane-anesthetized dogs (n = 6). Amitriptyline was intravenously administered in doses of 0.1, 1 and 10 mg/kg over 10 min every 20 min, which would provide approximately 1, 10 and 100 times higher plasma concentrations than a therapeutic one, respectively. The low dose hardly altered any of the cardiovascular variables...
June 14, 2017: Cardiovascular Toxicology
https://www.readbyqxmd.com/read/28613240/an-isoform-of-nedd4-2-plays-a-pivotal-role-in-electrophysiological-cardiac-abnormalities
#4
Shintaro Minegishi, Tomoaki Ishigami, Hisho Kawamura, Tabito Kino, Lin Chen, Rie Nakashima-Sasaki, Hiroshi Doi, Kengo Azushima, Hiromichi Wakui, Yumi Chiba, Kouichi Tamura
We have previously shown that neural precursor cell-expressed developmentally downregulated gene 4-2 (Nedd4-2) isoforms with a C2 domain are closely related to ubiquitination of epithelial sodium channel (ENaC), resulting in salt-sensitive hypertension by Nedd4-2 C2 targeting in mice. The sodium voltage-gated channel alpha subunit 5 (SCN5A) gene encodes the α subunit of the human cardiac voltage-gated sodium channel (I Na), and the potassium voltage-gated channel subfamily H member 2 (KCNH2) gene encodes rapidly activating delayed rectifier K channels (I Kr)...
June 14, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28606656/divergent-antiarrhythmic-effects-of-resveratrol-and-piceatannol-in-a-whole-heart-model-of-long-qt-syndrome
#5
Christian Ellermann, Julian Wolfes, Simon Kochhäuser, Dirk G Dechering, Florian Reinke, Kristina Wasmer, Lars Eckardt, Gerrit Frommeyer
BACKGROUND: The polyphenol resveratrol and its metabolite piceatannol have beneficial health effects including antiarrhythmic properties in ischemia/reperfusion. The objective of this study was to determine potential antiarrhythmic effects in acquired long-QT-syndrome (LQTS). METHODS AND RESULTS: 26 rabbit hearts were isolated and Langendorff-perfused. The IKr-blocker sotalol (100μM) was infused to mimic LQTS-2. Hearts were assigned to two groups. Sotalol significantly prolonged action potential duration (APD90) and QT-interval in both groups (group 1:APD90: +18ms, p<0...
June 3, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28600177/compound-heterozygous-kcnq1-mutations-a300t-p535t-in-a-child-with-sudden-unexplained-death-insights-into-possible-molecular-mechanisms-based-on-protein-modeling
#6
Erika Antúnez-Argüelles, Arturo Rojo-Domínguez, Ana Leticia Arregui-Mena, Leonor Jacobo-Albavera, Manlio Fabio Márquez, Pedro Iturralde-Torres, María Teresa Villarreal-Molina
Sudden death in a child is a devastating event with important medical implications for surviving relatives. Because it may be the first manifestation of unknown inherited cardiac disease, molecular autopsy can be helpful to determine the cause of death and identify at risk family members. The aim of the study was to perform a molecular autopsy in a seven year-old girl with sudden unexplained death, to find evidence supporting the possible pathogenicity of mutations identified in inherited cardiac disease genes, and to clinically and genetically assess first-degree relatives...
June 6, 2017: Gene
https://www.readbyqxmd.com/read/28595573/a-novel-kcnq1-nonsense-variant-in-the-isoform-specific-first-exon-causes-both-jervell-and-lange-nielsen-syndrome-1-and-long-qt-syndrome-1-a-case-report
#7
Motoi Nishimura, Marehiko Ueda, Ryota Ebata, Emi Utsuno, Takuma Ishii, Kazuyuki Matsushita, Osamu Ohara, Naoki Shimojo, Yoshio Kobayashi, Fumio Nomura
BACKGROUND: According to previous KCNQ1 (potassium channel, voltage gated, KQT-like subfamily, member 1) gene screening studies, missense variants, but not nonsense or frame-shift variants, cause the majority of long QT syndrome (LQTS; Romano-Ward syndrome [RWS]) 1 cases. Several missense variants are reported to cause RWS by a dominant-negative mechanism, and some KCNQ1 variants can cause both Jervell and Lange-Nielsen Syndrome (JLNS; in an autosomal recessive manner) and LQTS1 (in an autosomal dominant manner), while other KCNQ1 variants cause only JLNS...
June 8, 2017: BMC Medical Genetics
https://www.readbyqxmd.com/read/28592292/effects-of-amiodarone-on-short-qt-syndrome-variant-3-in-human-ventricles-a-simulation-study
#8
Cunjin Luo, Kuanquan Wang, Henggui Zhang
BACKGROUND: Short QT syndrome (SQTS) is a newly identified clinical disorder associated with atrial and/or ventricular arrhythmias and increased risk of sudden cardiac death (SCD). The SQTS variant 3 is linked to D172N mutation to the KCNJ2 gene that causes a gain-of-function to the inward rectifier potassium channel current (I K1), which shortens the ventricular action potential duration (APD) and effective refractory period (ERP). Pro-arrhythmogenic effects of SQTS have been characterized, but less is known about the possible pharmacological treatment of SQTS...
June 7, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28590366/effect-of-gwas-identified-genetic-variants-on-maximum-qt-interval-in-patients-with-schizophrenia-receiving-antipsychotic-agents-a-24-hour-holter-ecg-study
#9
Junzo Watanabe, Naoki Fukui, Yutaro Suzuki, Takuro Sugai, Shin Ono, Nobuto Tsuneyama, Mami Saito, Misuzu Tajiri, Toshiyuki Someya
BACKGROUND: Users of antipsychotics (APs) have a risk of sudden cardiac death (SCD). Sudden cardiac death in such patients is thought to be largely due to drug-induced QT prolongation. It has been reported that many subjects with drug-induced torsades de pointes (TdP) have risk alleles associated with subclinical congenital long QT syndrome. METHODS: We investigated the effects of the risk alleles associated with long QT on the QT interval in patients receiving APs using 24-hour Holter electrocardiograms to take into account the circadian fluctuation of QT intervals...
June 5, 2017: Journal of Clinical Psychopharmacology
https://www.readbyqxmd.com/read/28588847/a-case-of-long-qt-syndrome-challenges-on-a-bumpy-road
#10
Peter Magnusson, Per-Erik Gustafsson
Beta-agonist treatment during pregnancy may unmask the diagnosis of long QT syndrome. The QT prolongation can result in functional AV block. A history of seizure and/or sudden death in a family member should raise suspicion of ventricular tachycardia. More than one mutation may coexist. Refusal of beta-blocker therapy complicates risk stratification.
June 2017: Clinical Case Reports
https://www.readbyqxmd.com/read/28577045/prevalence-and-risk-factors-of-drug-associated-corrected-qt-prolongation-in-elderly-hospitalized-patients-results-of-a-retrospective-analysis-of-data-obtained-over-6%C3%A2-months
#11
Ophélie Maison, Blandine de la Gastine, Laurent Dayot, Sylvain Goutelle
OBJECTIVES: Little information exists on the frequency and determinants of drug-associated long QT syndrome in older adults. The objectives of this study were to assess the prevalence and identify risk factors of drug-associated long QT syndrome in a population of elderly hospitalized patients. METHODS: This was a retrospective study performed over 6 months in hospital geriatric medicine. Various QT-correction equations were fitted to the individual QT-RR data to evaluate the most appropriate equation...
June 2, 2017: Drugs & Aging
https://www.readbyqxmd.com/read/28576628/incidence-of-torsade-de-pointes-in-a-tertiary-hospital-population
#12
Eline Vandael, Bert Vandenberk, Joris Vandenberghe, Hilde Pincé, Rik Willems, Veerle Foulon
BACKGROUND: Multiple risk factors play a role in the development of QTc-prolongation and Torsade de Pointes (TdP). Cases of TdP are underreported and data on the incidence of TdP is scarce. The aim of this study was to investigate the incidence of TdP in a Belgian university hospital and describe the characteristics of TdP-cases using a risk score. METHODS: All cases from 2011 till 2013 coded with the ICD-9 code 427.1 in the University Hospitals of Leuven were selected...
May 19, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28562421/ventricular-fibrillation-and-long-qt-syndrome-due-to-panhypopituitarism
#13
Milena Aste, Cesare Capellini, Elisabetta Schiappacasse, Gianluigi Devoto, Michele Brignole
: A 68-year-old man presented with ventricular fibrillation and acquired long QT due to panhypopituitarism that disappeared completely within 48 h from replacement hormonal therapy. Panhypopituitarism is not well recognized as a reversible cause of ventricular fibrillation and long-QT syndrome in medical literature. In the present case, pituitary apoplexy exhausted an already chronically hypofunctioning pituitary gland, causing QT prolongation, torsades de pointes and several cardiac arrests due to ventricular fibrillation...
May 29, 2017: Journal of Cardiovascular Medicine
https://www.readbyqxmd.com/read/28552050/readthrough-of-scn5a-nonsense-mutations-r1623x-and-s1812x-question-gene-therapy-in-brugada-syndrome
#14
Siyong Teng, Jian Huang, Zhan Gao, Jie Hao, Yuejin Yang, Shu Zhang, Jielin Pu, Rutai Hui, Yongjian Wu, Zheng Fan
PURPOSE: Readthrough of nonsense mutation are used as gene-specific treatment in some genetic disease. Response to readthrough treatment is determined by readthrough efficiency of various nonsense mutations. In this manuscript, we aimed to explore the harmful effect of nonsense mutation suppressions. METHODS: HEK293 cells were transfected with two SCN5A (encode cardiac Na+ channel) nonsense mutations, p.R1623X and p.S1812X. We applied two readthrough-enhancing methods (either aminoglycosides or by a siRNA targeting eukaryotic release factor eRF3a (a GTPase that binds eRF1)) to suppress these SCN5A nonsense mutations...
May 28, 2017: Current Gene Therapy
https://www.readbyqxmd.com/read/28532774/genotype-positive-long-qt-syndrome-in-patients-with-coexisting-congenital-heart-disease
#15
Mohammed A Ebrahim, Matthew R Williams, Suzanne Shepard, James C Perry
Congenital long QT syndrome (LQTS) is characterized by QT prolongation with predisposition to life-threatening arrhythmia. There have been sporadic reports of LQTS coexisting with more common forms of congenital heart disease (CHD). However, the diagnosis of LQTS when CHD is present may be confounded by several common variables including postoperative electromechanical factors predisposing to ventricular arrhythmia, intrinsic, and postoperative QRS abnormalities. This report documents a single-center experience with patients who have both genetically confirmed LQTS and CHD to examine their modes of presentation and factors associated with making the diagnosis of LQTS in this patient population, as well as potential confounding variables that may mask or delay both LQTS diagnosis and initiation of therapy...
July 15, 2017: American Journal of Cardiology
https://www.readbyqxmd.com/read/28521025/mechanism-of-as2o3-induced-action-potential-prolongation-and-using-hips-cms-to-evaluate-the-rescue-efficacy-of-drugs-with-different-rescue-mechanism
#16
Meng Yan, Lifang Feng, Yanhui Shi, Junnan Wang, Yan Liu, Fengmei Li, Baoxin Li
Arsenic trioxide (As2O3) has been verified as a breakthrough in the management of acute promyelocytic leukemia in recent decades. However, cardiotoxicity, especially long QT syndrome (LQTS) has become the most important issue during As2O3 treatment. The characterized mechanisms behind this adverse effect are inhibition of cardiac hERG channel trafficking and increase of cardiac calcium currents. In our study, we found a new pathway underlying As2O3-induced cardiotoxicity that As2O3 accelerates lysosomal degradation of hERG on plasma membrane after using brefeldin A (BFA) to block protein trafficking...
May 17, 2017: Toxicological Sciences: An Official Journal of the Society of Toxicology
https://www.readbyqxmd.com/read/28506439/clinical-review-loperamide-toxicity
#17
REVIEW
Peter E Wu, David N Juurlink
Loperamide is a nonprescription opioid widely used for the treatment of diarrhea. Although it is relatively safe at therapeutic doses, increasing reports describe its misuse and abuse at very high doses either for euphoric effects or to attenuate symptoms of opioid withdrawal. Life-threatening loperamide toxicity can result from the relatively new clinical syndrome of loperamide-induced cardiac toxicity. These patients are often young and may present in cardiac arrest or with unheralded, recurrent syncope in conjunction with ECG abnormalities, including marked QT-interval prolongation, QRS-interval widening, and ventricular dysrhythmias...
May 13, 2017: Annals of Emergency Medicine
https://www.readbyqxmd.com/read/28490617/systemic-inflammation-as-a-novel-qt-prolonging-risk-factor-in-patients-with-torsades-de-pointes
#18
Pietro Enea Lazzerini, Franco Laghi-Pasini, Iacopo Bertolozzi, Gabriella Morozzi, Sauro Lorenzini, Antonella Simpatico, Enrico Selvi, Maria Romana Bacarelli, Francesco Finizola, Francesca Vanni, Deana Lazaro, Ademuyiwa Aromolaran, Nabil El Sherif, Mohamed Boutjdir, Pier Leopoldo Capecchi
OBJECTIVE: Increasing evidence indicates systemic inflammation as a new potential cause of acquired long QT syndrome (LQTS), via cytokine-mediated changes in cardiomyocyte ion channels. Torsade de pointes (TdP) is a life-threatening polymorphic ventricular tachycardia occurring in patients with LQTS, usually when multiple QT-prolonging factors are simultaneously present. Since classical risk factors cannot fully explain TdP events in a number of patients, we hypothesised that systemic inflammation may represent a currently overlooked risk factor contributing to TdP development in the general population...
May 10, 2017: Heart: Official Journal of the British Cardiac Society
https://www.readbyqxmd.com/read/28479515/phase-contrast-magnet-resonance-imaging-reveals-regional-transmural-and-base-to-apex-dispersion-of-mechanical-dysfunction-in-patients-with-long-qt-syndrome
#19
Johannes Brado, Markus J Dechant, Marius Menza, Adriana Komancsek, Corinna N Lang, Heiko Bugger, Daniela Foell, Bernd A Jung, Brigitte Stiller, Christoph Bode, Katja E Odening
BACKGROUND: Regional dispersion of prolonged repolarization is a hallmark of long QT syndrome (LQTS). We have also revealed regional heterogeneities in mechanical dysfunction in transgenic rabbit models of LQTS. OBJECTIVE: In this clinical pilot study, we investigated whether patients with LQTS exhibit dispersion of mechanical/diastolic dysfunction. METHODS: Nine pediatric patients with genotyped LQTS (12.2 ± 3.3 years) and 9 age- and sex-matched healthy controls (10...
May 4, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28470875/prolonged-corrected-qt-interval-in-the-donor-heart-is-there-a-risk
#20
Derek Leong, Tamar Aintablian, Michelle Kittleson, Michael Olymbios, Jignesh Patel, David H Chang, Jon Kobashigawa
BACKGROUND: Assessing the QT interval in donors is important to exclude long QT syndrome as the cause of death. A donor heart with a corrected QT (QTc)>500 msec is often concerning. We sought to evaluate first-year outcomes for donors with a QTc interval > 500 msec. METHODS: Between 2010 and 2014, we assessed 257 donor hearts for QTc interval > 500msec. Post-transplant outcomes included 1-year survival, 1-year freedom from any-treated rejection, 1- year freedom from CAV defined as stenosis ≥ 30% by angiography, and 1-year freedom from Non-Fatal Major Adverse Cardiac Events...
May 3, 2017: Clinical Transplantation
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