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Long qt syndrome

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https://www.readbyqxmd.com/read/28725320/splice-site-variants-in-the-kcnq1-and-scn5a-genes-transcript-analysis-as-a-tool-in-supporting-pathogenicity
#1
Ivone U S Leong, Philippa A Dryland, Debra O Prosser, Stella W-S Lai, Mandy Graham, Martin Stiles, Jackie Crawford, Jonathan R Skinner, Donald R Love
BACKGROUND: Approximately 75% of clinically definite long QT syndrome (LQTS) cases are caused by mutations in the KCNQ1, KCNH2 and SCN5A genes. Of these mutations, a small proportion (3.2-9.2%) are predicted to affect splicing. These mutations present a particular challenge in ascribing pathogenicity. METHODS: Here we report an analysis of the transcriptional consequences of two mutations, one in the KCNQ1 gene (c.781_782delinsTC) and one in the SCN5A gene (c.2437-5C>A), which are predicted to affect splicing...
August 2017: Journal of Clinical Medicine Research
https://www.readbyqxmd.com/read/28720088/sex-is-a-moderator-of-the-association-between-nos1ap-sequence-variants-and-qtc-in-two-long-qt-syndrome-founder-populations-a-pedigree-based-measured-genotype-association-analysis
#2
Annika Winbo, Eva-Lena Stattin, Ida Maria Westin, Anna Norberg, Johan Persson, Steen M Jensen, Annika Rydberg
BACKGROUND: Sequence variants in the NOS1AP gene have repeatedly been reported to influence QTc, albeit with moderate effect sizes. In the long QT syndrome (LQTS), this may contribute to the substantial QTc variance seen among carriers of identical pathogenic sequence variants. Here we assess three non-coding NOS1AP sequence variants, chosen for their previously reported strong association with QTc in normal and LQTS populations, for association with QTc in two Swedish LQT1 founder populations...
July 18, 2017: BMC Medical Genetics
https://www.readbyqxmd.com/read/28711156/towards-a-structural-view-of-drug-binding-to-herg-k-channels
#3
REVIEW
Jamie I Vandenberg, Eduardo Perozo, Toby W Allen
The human ether-a-go-go-related gene (hERG) K(+) channel is of great medical and pharmaceutical relevance. Inherited mutations in hERG result in congenital long-QT syndrome which is associated with a markedly increased risk of cardiac arrhythmia and sudden death. hERG K(+) channels are also remarkably susceptible to block by a wide range of drugs, which in turn can cause drug-induced long-QT syndrome and an increased risk of sudden death. The recent determination of the near-atomic resolution structure of the hERG K(+) channel, using single-particle cryo-electron microscopy (cryo-EM), provides tremendous insights into how these channels work...
July 12, 2017: Trends in Pharmacological Sciences
https://www.readbyqxmd.com/read/28699125/uptake-of-predictive-genetic-testing-and-cardiac-evaluation-for-children-at-risk-for-an-inherited-arrhythmia-or-cardiomyopathy
#4
Susan Christian, Joseph Atallah, Robin Clegg, Michael Giuffre, Cathleen Huculak, Tara Dzwiniel, Jillian Parboosingh, Sherryl Taylor, Martin Somerville
Predictive genetic testing in minors should be considered when clinical intervention is available. Children who carry a pathogenic variant for an inherited arrhythmia or cardiomyopathy require regular cardiac screening and may be prescribed medication and/or be told to modify their physical activity. Medical genetics and pediatric cardiology charts were reviewed to identify factors associated with uptake of genetic testing and cardiac evaluation for children at risk for long QT syndrome, hypertrophic cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy...
July 11, 2017: Journal of Genetic Counseling
https://www.readbyqxmd.com/read/28687226/acquired-long-qt-syndrome-and-phosphoinositide-3-kinase
#5
REVIEW
Ira S Cohen, Richard Z Lin, Lisa M Ballou
While it is well known that mutation of several different ion channels can cause congenital long QT syndrome, block of IKr is widely thought to be responsible for most cases of drug-induced acquired long QT syndrome (aLQTS). In this article, we review evidence supporting another cause of aLQTS due to inhibition of phosphoinositide 3-kinase (PI3K) signaling. Inhibition of PI3K affects multiple plateau currents, reducing IKr, IKs, and ICaL while increasing the persistent sodium current (INaP). The effects of PI3K inhibitors develop slowly, requiring hours to days to reach steady state...
May 17, 2017: Trends in Cardiovascular Medicine
https://www.readbyqxmd.com/read/28685698/medical-therapy-for-long-qt-syndrome
#6
George Adamos, Nicoletta Iacovidou, Theodoros Xanthos
Long QT syndrome (LQTS) is an arrhythmogenic disorder characterized by repolarization abnormalities with a propensity to cause life threatening cardiac events. The first manifestation of the syndrome may be sudden death, therefore, early diagnosis and therapy is of great importance. LQTS can be both congenital and acquired. The latter is most commonly seen in hospitalized patients and such individuals have an easily recognizable and reversible precipitating factor (electrolyte disturbances, certain drugs etc...
July 7, 2017: Mini Reviews in Medicinal Chemistry
https://www.readbyqxmd.com/read/28680407/cardiac-ion-channel-regulation-in-obesity-and-the-metabolic-syndrome-relevance-to-long-qt-syndrome-and-atrial-fibrillation
#7
REVIEW
Ademuyiwa S Aromolaran, Mohamed Boutjdir
Obesity and its associated metabolic dysregulation leading to metabolic syndrome is an epidemic that poses a significant public health problem. More than one-third of the world population is overweight or obese leading to enhanced risk of cardiovascular disease (CVD) incidence and mortality. Obesity predisposes to atrial fibrillation, ventricular, and supraventricular arrhythmias; conditions that are underlain by dysfunction in electrical activity of the heart. To date, current therapeutic options for cardiomyopathy of obesity are limited, suggesting that there is considerable room for development of therapeutic interventions with novel mechanisms of action that will help normalize rhythm in obese patients...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28679017/a-comparison-of-qtc-intervals-in-alcohol-withdrawal-patients-versus-acute-coronary-syndrome-patients
#8
Timothy Chu, Keith Azevedo, Amy A Ernst, Dusadee Sarangarm, Steven J Weiss
OBJECTIVES: Patients with an alcohol use disorder experiencing acute intoxication or withdrawal may be at risk for electrocardiograph (ECG) abnormalities, including prolongation of repolarization (long QTc [corrected QT]) that may contribute to arrhythmias and may be associated with a threefold increase in the likelihood of sudden cardiac events. Patients with acute coronary syndrome may have prolonged QTc as well. To our knowledge, no previous studies have compared the QTc of ACS with acute ethanol (EtOH) withdrawal syndromes in the emergency department (ED)...
July 2017: Southern Medical Journal
https://www.readbyqxmd.com/read/28673509/discovery-of-a-new-mexiletine-derived-agonist-of-the-herg-k-channel
#9
Roberta Gualdani, Maria Maddalena Cavalluzzi, Francesco Tadini-Buoninsegni, Giovanni Lentini
The human Ether-a-go-go Related Gene (hERG) potassium channel plays a central role in the rapid component (IKr) of cardiac action potential repolarization phase. A large number of structurally different compounds block hERG and cause a high risk of arrhythmias. Among the drugs that block hERG channel, a few compounds have been identified as hERG channel activators. Such compounds may be useful, at least in theory, for the treatment of long term QT syndrome. Here we describe a new activator of hERG channel, named MC450...
June 19, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28670758/congenital-long-qt-syndrome-and-torsade-de-pointes
#10
REVIEW
Nabil El-Sherif, Gioia Turitto, Mohamed Boutjdir
Since its initial description by Jervell and Lange-Nielsen in 1957, the congenital long QT syndrome (LQTS) has been the most investigated cardiac ion channelopathy. A prolonged QT interval in the surface electrocardiogram is the sine qua non of the LQTS and is a surrogate measure of the ventricular action potential duration (APD). Congenital as well as acquired alterations in certain cardiac ion channels can affect their currents in such a way as to increase the APD and hence the QT interval. The inhomogeneous lengthening of the APD across the ventricular wall results in dispersion of APD...
July 2, 2017: Annals of Noninvasive Electrocardiology
https://www.readbyqxmd.com/read/28663329/long-qt-syndrome-and-sudden-unexpected-infant-death
#11
EDITORIAL
Chantal Van Niekerk, Barbara Ströh Van Deventer, Lorraine du Toit-Prinsloo
Long QT syndrome (LQTS) is an inheritable primary electric disease of the heart characterised by abnormally long QT intervals and a propensity to develop atrial and ventricular tachyarrhythmias. It is caused by an inherited channelopathy responsible for sudden cardiac death in individuals with structurally normal hearts. Long QT syndrome can present early in life, and some studies suggest that it may be associated with up to 20% of sudden unexplained infant death (SUID), particularly when associated with external stressors such as asphyxia, which is commonly seen in many infant death scenes...
June 29, 2017: Journal of Clinical Pathology
https://www.readbyqxmd.com/read/28654209/sensitivity-and-reliability-of-halothane-anaesthetized-microminipigs-to-assess-risk-of-drug-induced-long-qt-syndrome
#12
Xin Cao, Takeshi Wada, Yuji Nakamura, Suchitra Matsukura, Hiroko Izumi-Nakaseko, Kentaro Ando, Atsuhiko T Naito, Atsushi Sugiyama
Using moxifloxacin and terfenadine, which are known to induce benign and malignant QT interval prolongation, respectively, we analysed whether halothane-anaesthetized microminipigs are an appropriate model for assessing the risk of drug-induced long QT syndrome. Moxifloxacin (0.03, 0.3 and 3 mg/kg) and terfenadine (0.03, 0.3 and 3 mg/kg) were intravenously infused over 10 min. with a pause of 20 min. to the halothane-anaesthetized microminipigs (n=4 for each drug). Moxifloxacin decreased the heart rate, whereas it increased the blood pressure in a dose-related manner...
June 27, 2017: Basic & Clinical Pharmacology & Toxicology
https://www.readbyqxmd.com/read/28648120/long-qt-syndrome-associated-caveolin-3-mutations-differentially-regulate-the-hyperpolarization-activated-cyclic-nucleotide-gated-channel-4
#13
L J Motloch, R Larbig, T Darabi, S Reda, K A Motloch, B Wernly, M Lichtenauer, T Gebing, A Schwaiger, N Zagidullin, M Wolny, U C Hoppe
Background Caveolin-3 (cav-3) mutations are linked to the long-QT syndrome (LQTS) causing distinct clinical symptoms. Hyperpolarization-activated cyclic nucleotide channel 4 (HCN4) underlies the pacemaker current If. It associates with cav-3 and both form a macromolecular complex. Methods To examine the effects of human LQTS-associated cav-3 mutations on HCN4-channel function, HEK293-cells were cotransfected with HCN4 and wild-type (WT) cav-3 or a LQTS-associated cav-3 mutant (T78M, A85T, S141R, or F97C). HCN4 currents were recorded using the whole-cell patch-clamp technique...
June 26, 2017: Physiology International
https://www.readbyqxmd.com/read/28629851/another-piece-of-the-puzzle-assessment-of-mechanical-dispersion-by-magnetic-resonance-in-long-qt-syndrome
#14
EDITORIAL
Elena Arbelo
No abstract text is available yet for this article.
June 16, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28623018/spiked-helmet-sign-after-percutaneous-left-stellate-ganglion-ablation-in-a-patient-with-long-qt-syndrome
#15
Farid Aliyev, Vugar Abdulkerimov, Enes Elvin Gul, Fuad Samedov, Elnur Isayev, Elnur Ferecov
"Spiked helmet" is a type of ST elevation, which is generally observed in critically ill patients and associated with very poor prognosis. Here we present a case of previously undiagnosed long QT syndrome admitted with polymorphic ventricular tachycardia (PMVT) unresponsive to pharmacological treatment and developed "spiked helmet" sign after left percutaneous stellate ganglion ablation.
June 9, 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/28619993/low-extracellular-potassium-prolongs-repolarization-and-evokes-early-afterdepolarization-in-human-induced-pluripotent-stem-cell-derived-cardiomyocytes
#16
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
#17
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/28616568/clinical-evaluation-of-r860q-semi-conservative-amino-acid-substitution-in-cacna1c-gene-in-association-with-long-qt-syndrome
#18
Usama Boles, Chris Simpson, Enes E Gul, Cortney Kiss, Andres Enriquez, Zongchao Jia, Adrián Baranchuk, Jagdeep S Walia
No abstract text is available yet for this article.
June 2017: IJC Heart & Vasculature
https://www.readbyqxmd.com/read/28607621/epicardially-placed-implantable-cardioverter-defibrillator-for-a-child-with-congenital-long-qt-syndrome
#19
Hirotaro Sugiyama, Motomi Tachibana, Hiroshi Morita, Nobuhiro Nishii, Akihito Miyoshi, Hiroyasu Sugiyama, Koji Nakagawa, Atsuyuki Watanabe, Kazufumi Nakamura, Hiroshi Ito
A 7-year-old boy presented at our hospital with syncope. At birth, electrocardiography had shown a long QT interval with torsade de pointes (TdP). Congenital long QT syndrome (LQTS) had been diagnosed by genetic testing, and was successfully controlled with oral propranolol. At age 7, TdP had recurred with syncope. Electrocardiography revealed a prominent long QT interval with T-wave alternans. The propranolol dose was increased, but TdP remained uncontrolled. A cardioverter-defibrillator (ICD) was implanted epicardially, and TdP completely resolved with atrial pacing...
June 2017: Journal of Arrhythmia
https://www.readbyqxmd.com/read/28606656/divergent-antiarrhythmic-effects-of-resveratrol-and-piceatannol-in-a-whole-heart-model-of-long-qt-syndrome
#20
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
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