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Long qt syndrome

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https://www.readbyqxmd.com/read/29650124/phenotypic-landscape-and-risk-management-in-long-qt-syndrome-nudging-forward
#1
EDITORIAL
Andrew A Grace, Gareth D K Matthews
No abstract text is available yet for this article.
April 17, 2018: Journal of the American College of Cardiology
https://www.readbyqxmd.com/read/29650123/interplay-between-genetic-substrate-qtc-duration-and-arrhythmia-risk-in-patients-with-long-qt-syndrome
#2
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/29648704/abnormal-ventricular-repolarization-in-long-qt-syndrome-carriers-is-related-to-short-left-ventricular-filling-time-and-attenuated-stroke-volume-response-during-exercise
#3
Dafni Charisopoulou, George Koulaouzidis, Annika Rydberg, Michael Y Henein
BACKGROUND: Long QT syndrome (LQTS) carriers are characterized by abnormal ventricular repolarization, prolonged systole, and mechanical dispersion. Prolonged left ventricular (LV) systole has been shown to result in disproportionate shortening of LV filling in other conditions. The aim of this study was to assess LV filling, diastolic function, and stroke volume (SV) response to dynamic exercise, in a group of LQTS carriers. METHODS: Forty-seven LQTS carriers (45 ± 15 years, 20 symptomatic) and 35 healthy individuals underwent bicycle stress echocardiogram...
April 12, 2018: Echocardiography
https://www.readbyqxmd.com/read/29625280/long-qt-syndrome-type-5-lite-defining-the-clinical-phenotype-associated-with-the-potentially-pro-arrhythmic-p-asp85asn-kcne1-common-genetic-variant
#4
Conor Lane, John R Giudicessi, Dan Ye, David J Tester, Ram K Rohatgi, J Martijn Bos, Michael J Ackerman
BACKGROUND: Long QT syndrome (LQTS) genetic test reports commonly exclude potentially pro-arrhythmic common variants such as p.Asp85Asn-KCNE1. OBJECTIVE: To determine if a discernible phenotype is associated with p.Asp85Asn-KCNE1 and if relatively common KCNE1 variants underlie transient QT prolongation pedigrees with negative commercial LQTS genetic tests. METHODS: Retrospective review was used to compare demographics, symptomatology, and QT parameters of individuals with p...
April 3, 2018: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/29624510/genetic-risk-stratification-in-cardiac-arrhythmias
#5
Carlo Napolitano, Andrea Mazzanti, Silvia G Priori
PURPOSE OF REVIEW: The current article provides a concise summary of the possibilities and limitations of genotype-based risk stratification of cardiac arrhythmias. We will outline the most important findings of the recent years in the light of their chronological and conceptual development. RECENT FINDINGS: Genotype-phenotype association studies in families with single-gene disorders as well as in the general population led to the discovery of several DNA variants significantly associated with the risk of sudden death or life-threatening arrhythmias...
April 4, 2018: Current Opinion in Cardiology
https://www.readbyqxmd.com/read/29622001/clinical-and-molecular-genetic-risk-determinants-in-adult-long-qt-syndrome-type-1-and-2-patients-koponen-et-al-follow-up-of-adult-lqts-patients
#6
Mikael Koponen, Aki S Havulinna, Annukka Marjamaa, Annukka M Tuiskula, Veikko Salomaa, Päivi J Laitinen-Forsblom, Kirsi Piippo, Lauri Toivonen, Kimmo Kontula, Matti Viitasalo, Heikki Swan
BACKGROUND: Long QT syndrome (LQTS) is an inherited cardiac disorder predisposing to sudden cardiac death (SCD). We studied factors affecting the clinical course of genetically confirmed patients, in particular those not receiving β-blocker treatment. In addition, an attempt was made to associate risk of events to specific types of KCNQ1 and KCNH2 mutations. METHODS: A follow-up study covering a mean of 18.6 ± 6.1 years was conducted in 867 genetically confirmed LQT1 and LQT2 patients and 654 non-carrier relatives aged 18-40 years...
April 5, 2018: BMC Medical Genetics
https://www.readbyqxmd.com/read/29619572/-recognizing-rare-cardiac-diseases-by-electrocardiogram
#7
REVIEW
W Grimm, A Grimm, K Grimm, E Efimova
A number of rare cardiac diseases can be recognized by electrocardiogram (ECG). This article illustrates the clinical importance of ECG as a key diagnostic tool to detect Wolff-Parkinson-White syndrome and channelopathies, which are frequently diagnosed late after one or more affected family members have become victims of sudden cardiac death. These channelopathies include long QT syndrome, short QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia. In addition, typical ECG findings are frequently present in patients with idiopathic ventricular tachycardia, arrhythmogenic right ventricular dysplasia, digitalis intoxication, hyperkalemia, acute cor pulmonale due to pulmonary embolism, as well as severe left ventricular hypertrophy as in hypertrophic cardiomyopathy...
April 4, 2018: Der Internist
https://www.readbyqxmd.com/read/29616748/electrocardiographic-t-wave-parameters-in-families-with-long-qt-syndrome
#8
Grażyna Markiewicz-Łoskot, Ewa Moric-Janiszewska, Bogusław Mazurek, Marianna Łoskot, Mariola Bartusek, Agnieszka Skierska, Lesław Szydłowski
BACKGROUND: T-wave parameters, especially the Tpeak-Tend interval (TpTe), reflect the total dispersion of repolarization, whose amplification may lead to the development of life-threatening ventricular arrhythmias observed in the long QT syndrome (LQTS). OBJECTIVES: The study attempted to evaluate QT, QTp (Q-Tpeak) and TpTe (Tpeak-Tend) intervals in unaffected and affected blood relatives of children with clinically confirmed LQTS as well as to determine whether the values of these repolarization parameters may be used in clinical practice...
March 21, 2018: Advances in Clinical and Experimental Medicine: Official Organ Wroclaw Medical University
https://www.readbyqxmd.com/read/29582428/selective-late-sodium-current-inhibitor-gs-458967-suppresses-torsades-de-pointes-by-mostly-affecting-perpetuation-but-not-initiation-of-the-arrhythmia
#9
Alexandre Bossu, Marien J C Houtman, Veronique M F Meijborg, Rosanne Varkevisser, Henriette D M Beekman, Albert Dunnink, Jacques M T de Bakker, Nevena Mollova, Sridharan Rajamani, Luiz Belardinelli, Marcel A G van der Heyden, Marc A Vos
BACKGROUND AND PURPOSE: Enhanced late sodium current (late INa ) in heart failure and long QT syndrome type 3 is proarrhythmic. GS-458967 (GS967) is a selective and potent late INa inhibitor. This study aimed to evaluate the antiarrhythmic effect of late INa inhibition by GS967 in the chronic atrioventricular block (CAVB) dog model sensitive to Torsade de Pointes arrhythmias (TdP) and to elucidate its electrophysiological mode of action in vivo and in vitro. METHODS - RESULTS: GS967 (IC50 for late INa ~ 200 nM) markedly shortened action potential duration of canine ventricular cardiomyocytes and repolarization parameters in vivo in sinus rhythm (SR, n=10) dogs, in a concentration-dependent manner...
March 27, 2018: British Journal of Pharmacology
https://www.readbyqxmd.com/read/29582136/unexplained-cardiac-arrest-a-tale-of-conflicting-interpretations-of-kcnq1-genetic-test-results
#10
Han Chow Chua, Helge Servatius, Babken Asatryan, André Schaller, Claudine Rieubland, Fabian Noti, Jens Seiler, Laurent Roten, Samuel H Baldinger, Hildegard Tanner, Juerg Fuhrer, Andreas Haeberlin, Anna Lam, Stephan A Pless, Argelia Medeiros-Domingo
OBJECTIVE: Unexplained cardiac arrest (UCA) is often the first manifestation of an inherited arrhythmogenic disease. Genetic testing in UCA is challenging due to the complexities of variant interpretation in the absence of supporting cardiac phenotype. We aimed to investigate if a KCNQ1 variant [p.(Pro64_Pro70del)], previously reported as pathogenic, contributes to the long-QT syndrome phenotype, co-segregates with disease or affects KCNQ1 function in vitro. METHODS: DNA was extracted from peripheral blood of a 22-year-old male after resuscitation from UCA...
March 26, 2018: Clinical Research in Cardiology: Official Journal of the German Cardiac Society
https://www.readbyqxmd.com/read/29581800/impact-of-drug-induced-long-qt-syndrome-a-systematic-review
#11
Karuppiah Arunachalam, Seetha Lakshmanan, Abhishek Maan, Narendra Kumar, Paari Dominic
Background: Drug induced long QT syndrome is quite common in daily clinical practice but its impact is unknown. Methods: PubMed and EMBASE databases (until May 2, 2017) were searched to identify studies reporting drug induced long QT syndrome and followed the PRISMA guidelines. The main outcomes measured in these studies were QTc prolongation, ventricular arrhythmias, torsade de pointes (TdP) and death. Results: Out of 176 non-duplicate reports, 36 studies satisfied inclusion criteria and provided data on patients exposed to drugs that can potentially cause long QT...
May 2018: Journal of Clinical Medicine Research
https://www.readbyqxmd.com/read/29575607/the-maximum-qtc-of-holter-electrocardiography-in-a-pediatric-population
#12
Yoshiharu Ogawa, Toshikatsu Tanaka, Sachiko Kido
BACKGROUND: The corrected QT interval (QTc) of electrocardiograms (ECGs) at rest and after exercise in a short daytime recording period may be insufficient for the diagnosis and management of long QT syndrome (LQTS) patients, especially for those with LQTS type 2 and 3. Therefore, examining QTc using Holter ECG is important. We designed a method of analyzing QTc in Holter ECG that can be performed in daily clinical practice by combining automatic and manual measurements. METHODS: We reviewed the charts of healthy children (n=210) and LQTS patients (n=35) aged <16 years and analyzed QTc at rest, after exercise, and the maximum QTc of Holter ECG...
March 25, 2018: Pediatrics International: Official Journal of the Japan Pediatric Society
https://www.readbyqxmd.com/read/29573040/f463l-increases-the-potential-of-dofetilide-on-human-ether-a-go-go-related-gene-herg-channels
#13
Gong Cheng, Jine Wu, Wenqi Han, Chaofeng Sun
Mutations in genes related to long QT syndrome (LQTS) is recognized as an independent risk of drug-induced LQTS. We previously screened a mutation F463L in a Chinese patient with LQT2, syncope, and epilepsy. Here, we planned to illustrate how F463L influences the action of dofetilide on hERG channels. F463L-hERG plasmids were transfected into the stable Human Embryonic Kidney 293 (HEK293) cells expressing WT-hERG to generate heterozygous mutant (WT + F463L-hERG). Whole-cell patch clamp and laser confocal scanning microscopy were used to evaluate electrophysiological consequences and the membrane distribution of hERG protein...
March 23, 2018: Microscopy Research and Technique
https://www.readbyqxmd.com/read/29566261/effects-of-trimethoprim-sulfadiazine-and-detomidine-on-the-function-of-equine-k-v-11-1-channels-in-a-two-electrode-voltage-clamp-tevc-oocyte-model
#14
D S Trachsel, M A Tejada, V Groesfjeld Christensen, P J Pedersen, J K Kanters, R Buhl, K Calloe, D A Klaerke
The long QT syndrome (LQTS) is a channelopathy that can lead to severe arrhythmia and sudden cardiac death. Pharmacologically induced LQTS is caused by interaction between drugs and potassium channels, especially the Kv 11.1 channel. Due to such interactions, numerous drugs have been withdrawn from the market or are administered with precautions in human medicine. However, some compounds, such as trimethoprim-sulfonamide combinations are still widely used in veterinarian medicine. Therefore, we investigate the effect of trimethoprim-sulfadiazine (TMS), trimethoprim, sulfadiazine, and detomidine on equine-specific Kv 11...
March 22, 2018: Journal of Veterinary Pharmacology and Therapeutics
https://www.readbyqxmd.com/read/29550817/molecular-insights-into-herg-potassium-channel-blockade-by-lubeluzole
#15
Roberta Gualdani, Maria Maddalena Cavalluzzi, Francesco Tadini-Buoninsegni, Marino Convertino, Philippe Gailly, Anna Stary-Weinzinger, Giovanni Lentini
BACKGROUND/AIMS: Lubeluzole is a benzothiazole derivative that has shown neuroprotective properties in preclinical models of ischemic stroke. However, clinical research on lubeluzole is now at a standstill, since lubeluzole seems to be associated with the acquired long QT syndrome and ventricular arrhythmias. Since the cardiac cellular effects of lubeluzole have not been described thus far, an explanation for the lubeluzole-induced QT interval prolongation is lacking. METHODS: We tested the affinity of lubeluzole, its enantiomer, and the racemate for hERG channel using the patch-clamp technique...
March 10, 2018: Cellular Physiology and Biochemistry
https://www.readbyqxmd.com/read/29550106/meta-analysis-of-t-peak-t-end-and-t-peak-t-end-qt-ratio-for-risk-stratification-in-congenital-long-qt-syndrome
#16
Gary Tse, Mengqi Gong, Lei Meng, Cheuk Wai Wong, Stamatis Georgopoulos, George Bazoukis, Martin C S Wong, Konstantinos P Letsas, Vassilios S Vassiliou, Yunlong Xia, Adrian M Baranchuk, Gan-Xin Yan, Tong Liu
BACKGROUND AND OBJECTIVES: Congenital long QT syndrome (LQTS) predisposes affected individuals to ventricular tachycardia/fibrillation (VF/VF), potentially resulting in sudden cardiac death. The Tpeak -Tend interval and the Tpeak -Tend /QT ratio, electrocardiographic markers of dispersion of ventricular repolarization, were proposed for risk stratification but their predictive values in LQTS have been controversial. A systematic review and meta-analysis was conducted to examine the value of Tpeak -Tend intervals and Tpeak -Tend /QT ratios in predicting arrhythmic and mortality outcomes in congenital LQTS...
March 6, 2018: Journal of Electrocardiology
https://www.readbyqxmd.com/read/29548277/common-variants-in-the-herg-kcnh2-voltage-gated-potassium-channel-are-associated-with-altered-fasting-and-glucose-stimulated-plasma-incretin-and-glucagon-responses
#17
Line Engelbrechtsen, Yuvaraj Mahendran, Anna Jonsson, Anette Prior Gjesing, Peter E Weeke, Marit E Jørgensen, Kristine Færch, Daniel R Witte, Jens J Holst, Torben Jørgensen, Niels Grarup, Oluf Pedersen, Henrik Vestergaard, Signe Torekov, Jørgen K Kanters, Torben Hansen
BACKGROUND: Patients with long QT syndrome due to rare loss-of-function mutations in the human ether-á-go-go-related gene (hERG) have prolonged QT interval, risk of arrhythmias, increased secretion of insulin and incretins and impaired glucagon response to hypoglycemia. This is caused by a dysfunctional Kv11.1 voltage-gated potassium channel. Based on these findings in patients with rare variants in hERG, we hypothesized that common variants in hERG may also lead to alterations in glucose homeostasis...
March 16, 2018: BMC Genetics
https://www.readbyqxmd.com/read/29545312/-structural-implications-of-herg-k-channel-block-by-a-high-affinity-minimally-structured-blocker
#18
Matthew V Helliwell, Yihong Zhang, Aziza El Harchi, Chunyun Du, Jules C Hancox, Christopher E Dempsey
Cardiac potassium channels encoded by human Ether-à-go-go Related Gene (hERG) are major targets for structurally diverse drugs associated with acquired long QT syndrome. This study characterized hERG channel inhibition by a minimally structured high affinity hERG inhibitor, Cavalli-2, composed of three phenyl groups linked by polymethylene spacers around a central amino group, chosen to probe the spatial arrangement of side chain groups in the high-affinity drug binding site of the hERG pore. hERG current (IhERG ) recorded at physiological temperature from HEK 293 cells was inhibited with an IC50 of 35...
March 15, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29540853/the-voltage-gated-sodium-channel-ef-hands-form-an-interaction-with-the-iii-iv-linker-that-is-disturbed-by-disease-causing-mutations
#19
Bernd R Gardill, Ricardo E Rivera-Acevedo, Ching-Chieh Tung, Mark Okon, Lawrence P McIntosh, Filip Van Petegem
Voltage-gated sodium channels (NaV ) are responsible for the rapid depolarization of many excitable cells. They readily inactivate, a process where currents diminish after milliseconds of channel opening. They are also targets for a multitude of disease-causing mutations, many of which have been shown to affect inactivation. A cluster of disease mutations, linked to Long-QT and Brugada syndromes, is located in a C-terminal EF-hand like domain of NaV 1.5, the predominant cardiac sodium channel isoform. Previous studies have suggested interactions with the III-IV linker, a cytosolic element directly involved in inactivation...
March 14, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29532034/mechanisms-of-kcnq1-channel-dysfunction-in-long-qt-syndrome-involving-voltage-sensor-domain-mutations
#20
Hui Huang, Georg Kuenze, Jarrod A Smith, Keenan C Taylor, Amanda M Duran, Arina Hadziselimovic, Jens Meiler, Carlos G Vanoye, Alfred L George, Charles R Sanders
Mutations that induce loss of function (LOF) or dysfunction of the human KCNQ1 channel are responsible for susceptibility to a life-threatening heart rhythm disorder, the congenital long QT syndrome (LQTS). Hundreds of KCNQ1 mutations have been identified, but the molecular mechanisms responsible for impaired function are poorly understood. We investigated the impact of 51 KCNQ1 variants with mutations located within the voltage sensor domain (VSD), with an emphasis on elucidating effects on cell surface expression, protein folding, and structure...
March 2018: Science Advances
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