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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
#1
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/29789915/a-potential-diagnostic-approach-for-foetal-long-qt-syndrome-developed-and-validated-in-children
#2
Arja Suzanne Vink, Irene M Kuipers, Rianne H A C M De Bruin-Bon, Arthur A M Wilde, Nico A Blom, Sally-Ann B Clur
In patients with Long-QT Syndrome (LQTS), mechanical abnormalities have been described. Recognition of these abnormalities could potentially be used in the diagnosis of LQTS, especially in the foetus where an ECG is not available and DNA-analysis is invasive. We aimed to develop and validate a marker for these mechanical abnormalities in children and to test its feasibility in foetuses as a proof of principle. We measured the myocardial contraction duration using colour Tissue Doppler Imaging (cTDI) in 41 LQTS children and age- and gender-matched controls...
May 22, 2018: Pediatric Cardiology
https://www.readbyqxmd.com/read/29787427/impact-of-ionizing-radiation-on-electrophysiological-behavior-of-human-induced-ipsc-derived-cardiomyocytes-on-multielectrode-arrays
#3
Benjamin V Becker, Thomas Seeger, Thomas Beiert, Markus Antwerpen, Andreas Palnek, Matthias Port, Reinhard Ullmann
Cardiac arrhythmia presumably induced through cardiac fibrosis is a recurrent long-term consequence of exposure to ionizing radiation. However, there is also evidence that cardiac arrhythmia can occur in patients shortly after irradiation. In this study, the authors employed multielectrode arrays to investigate the short-term effects of x-ray radiation on the electrophysiological behavior of cardiomyocytes derived from human-induced pluripotent stem cells. These cardiomyocytes with spontaneous pacemaker activity were cultured on single-well multielectrode arrays...
July 2018: Health Physics
https://www.readbyqxmd.com/read/29784533/long-qt-syndrome-a-comprehensive-review-of-the-literature-and-current-evidence
#4
REVIEW
Syed Raza Shah, Ki Park
Long QT syndrome (LQT) represents a heterogeneous family of cardiac electrophysiologic disorders characterized by QT prolongation and T-wave abnormalities on the electrocardiogram. It is commonly associated with syncope, however, sudden cardiac death can occur due to torsades de pointes. LQT is a clinical diagnosis and should be suspected in individuals on the basis of clinical presentation, family history and electrocardiogram characteristics. Management is focused on the prevention of syncope and ultimately sudden death...
May 10, 2018: Current Problems in Cardiology
https://www.readbyqxmd.com/read/29772517/dynamics-of-the-hazard-for-distant-metastases-after-ipsilateral-breast-tumor-recurrence-according-to-estrogen-receptor-status-an-analysis-of-2851-patients
#5
Massimiliano Gennaro, Serena Di Cosimo, Ilaria Ardoino, Silvia Veneroni, Luigi Mariani, Roberto Agresti, Maria Grazia Daidone, Filippo de Braud, Giovanni Apolone, Elia Biganzoli, Romano Demicheli
BACKGROUND: Breast cancer (BC) patients with ipsilateral breast tumor recurrence (IBTR) are at high risk of developing distant metastases (DM). We aimed to evaluate the risk pattern of developing DM, with respect to the occurrence of IBTR, in a large series of patients homogeneously treated by conservative surgery (QUART) with a considerably long follow-up. METHODS: Piecewise exponential model was used to investigate DM dynamics conditioning on known prognostic factors and IBTR occurrence as time dependent covariate...
May 14, 2018: Breast: Official Journal of the European Society of Mastology
https://www.readbyqxmd.com/read/29769222/transient-outward-k-current-i-to-underlies-the-right-ventricular-initiation-of-polymorphic-ventricular-tachycardia-in-a-transgenic-rabbit-model-of-long-qt-syndrome-type-1
#6
Bum-Rak Choi, Weiyan Li, Dmitry Terentyev, Anatoli Y Kabakov, Mingwang Zhong, Colin M Rees, Radmila Terentyeva, Tae Yun Kim, Zhilin Qu, Xuwen Peng, Alain Karma, Gideon Koren
BACKGROUND: Sudden death in long-QT syndrome type 1 (LQT1), an inherited disease caused by loss-of-function mutations in KCNQ1, is triggered by early afterdepolarizations (EADs) that initiate polymorphic ventricular tachycardia (pVT). We investigated ionic mechanisms that underlie pVT in LQT1 using a transgenic rabbit model of LQT1. METHODS: Optical mapping, cellular patch clamping, and computer modeling were used to elucidate the mechanisms of EADs in transgenic LQT1 rabbits...
June 2018: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/29766267/-syncopes-and-channelopathies
#7
REVIEW
Johanna Müller-Leisse, Christos Zormpas, Thorben König, David Duncker, Christian Veltmann
Syncope can be the first manifestation of cardiac channelopathies, namely Brugada syndrome, long QT syndrome, short QT syndrome and catecholaminergic polymorphic ventricular tachycardia (CPVT). Patients affected by these rare diseases are at increased risk for sudden cardiac death due to ventricular tachyarrhythmias and require specific therapy and follow-up. As syncope is common in the general population, only few cases are caused by an underlying channelopathy. Nevertheless, the diagnosis should be considered in young patients with structurally normal hearts, especially if the history of syncope is typical for an arrhythmogenic cause, in the presence of characteristic echocardiogram (ECG) patterns, and if there is a family history of channelopathies or sudden cardiac death...
May 15, 2018: Herzschrittmachertherapie & Elektrophysiologie
https://www.readbyqxmd.com/read/29764897/diagnostic-yield-of-genetic-testing-in-young-athletes-with-t-wave-inversion
#8
Nabeel Sheikh, Michael Papadakis, Mathew Wilson, Aneil Malhotra, Carmen Adamuz, Tessa Homfray, Lorenzo Monserrat, Elijah R Behr, Sanjay Sharma
Background -T-wave inversion (TWI) is common in patients with cardiomyopathy. However, up to 25% of athletes of African/Afro-Caribbean descent (black athletes) and 5% of white athletes also have TWI of unclear clinical significance despite comprehensive clinical evaluation and long-term follow-up. The aim of this study was to determine the diagnostic yield from genetic testing, beyond clinical evaluation, when investigating athletes with TWI. Methods -We investigated 50 consecutive asymptomatic black and 50 white athletes aged 14-35-years-old with TWI and a normal echocardiogram who were referred to a UK tertiary center for cardiomyopathy and sports cardiology...
May 15, 2018: Circulation
https://www.readbyqxmd.com/read/29759629/circadian-variation-of-ventricular-arrhythmias-in-catecholaminergic-polymorphic-ventricular-tachycardia
#9
Christina Y Miyake, S Yukiko Asaki, Gregory Webster, Richard J Czosek, Joseph Atallah, Kishor Avasarala, Sri O Rao, Patricia E Thomas, Jeffrey J Kim, Santiago O Valdes, Caridad de la Uz, Yunfei Wang, Xander H T Wehrens, Dominic Abrams
OBJECTIVES: The aim of this paper was to investigate whether ventricular arrhythmias in children with catecholaminergic polymorphic ventricular tachycardia (CPVT) show circadian patterns. BACKGROUND: Circadian arrhythmic patterns have been established in long QT, Brugada, and early repolarization, but have not been investigated in CPVT. METHODS: This is a multicenter, retrospective review of pediatric CPVT patients, age <21 years at diagnosis...
November 2017: JACC. Clinical Electrophysiology
https://www.readbyqxmd.com/read/29758301/lipid-roles-in-herg-function-and-interactions-with-drugs
#10
REVIEW
Meruyert Kudaibergenova, Laura L Perissinotti, Sergei Y Noskov
Human-ether-a-go-go-related channel (hERG) is a voltage gated potassium channel (Kv 11.1) abundantly expressed in heart and brain tissues. In addition to playing an important role in mediation of repolarizing K+ currents (IKr ) in Action Potential (AP), hERG is notorious for its propensity to interact with various medications. The drug-induced block of K+ currents across hERG channel are strongly associated with dysrhythmic conditions collectively known as drug-induced long-QT-syndrome. The recent availability of the high-resolution Cryo-EM structures for the hERG channel has provided unique opportunity to resolve structural mechanisms involved into the process of voltage-gating of hERG channels, map various roles played by components of ventricular and neuronal membranes and then to connect it to cellular pathways through which diverse chemical compounds might be affecting function of the channel...
May 11, 2018: Neuroscience Letters
https://www.readbyqxmd.com/read/29756425/long-qt-interval-induced-by-clindamycin-a-case-report
#11
P B Maduranga, K C Chathurangani, C J Dharmaratne, U D De silva
No abstract text is available yet for this article.
March 31, 2018: Ceylon Medical Journal
https://www.readbyqxmd.com/read/29754926/another-step-towards-a-mechanism-based-subtype-specific-therapy-in-long-qt-syndrome
#12
EDITORIAL
Katja E Odening
No abstract text is available yet for this article.
July 15, 2018: International Journal of Cardiology
https://www.readbyqxmd.com/read/29754923/enhanced-late-sodium-current-underlies-pro-arrhythmic-intracellular-sodium-and-calcium-dysregulation-in-murine-sodium-channelopathy
#13
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/29752375/functional-invalidation-of-putative-sudden-infant-death-syndrome-associated-variants-in-the-kcnh2-encoded-kv11-1-channel
#14
Jennifer L Smith, David J Tester, Allison R Hall, Don E Burgess, Chun-Chun Hsu, Samy Claude Elayi, Corey L Anderson, Craig T January, Jonathan Z Luo, Dustin N Hartzel, Uyenlinh L Mirshahi, Michael F Murray, Tooraj Mirshahi, Michael J Ackerman, Brian P Delisle
BACKGROUND: Heterologous functional validation studies of putative long-QT syndrome subtype 2-associated variants clarify their pathological potential and identify disease mechanism(s) for most variants studied. The purpose of this study is to clarify the pathological potential for rare nonsynonymous KCNH2 variants seemingly associated with sudden infant death syndrome. METHODS: Genetic testing of 292 sudden infant death syndrome cases identified 9 KCNH2 variants: E90K, R181Q, A190T, G294V, R791W, P967L, R1005W, R1047L, and Q1068R...
May 2018: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/29746361/prolonged-qrs-widening-after-aripiprazole-overdose
#15
Maryann Mazer-Amirshahi, Robert Porter, Kayla Dewey
BACKGROUND: Aripiprazole is an atypical antipsychotic with a long half-life. Overdose can result in protracted somnolence and cardiac disturbances, particularly QT interval prolongation. METHODS: This is a single case report of a 14-year-old boy who took an overdose of aripiprazole and developed QRS widening. CASE: A 14-year-old boy intentionally ingested 20 tablets of aripiprazole (5 mg). He was brought to the emergency department when his ingestion was discovered...
May 5, 2018: Pediatric Emergency Care
https://www.readbyqxmd.com/read/29744527/inherited-primary-arrhythmia-disorders-cardiac-channelopathies-and-sports-activity
#16
REVIEW
S Marrakchi, I Kammoun, E Bennour, L Laroussi, M Ben Miled, S Kachboura
Sudden cardiac death (SCD) in an apparently healthy individual is a tragedy. It is important to identify the cause of death and to prevent SCD in potentially at-risk family members. Inherited primary arrhythmia disorders are associated with exercise-related SCD. Despite the well-known benefits of exercise, exercise restriction has been a historical mainstay of therapy for these conditions. However, since familiarity with inherited arrhythmia conditions has increased and patients are often children and young adults, it is necessary to reassess the treatment guidelines regarding exercise constraints...
May 9, 2018: Herz
https://www.readbyqxmd.com/read/29740400/the-role-of-kcnq1-mutations-and-maternal-beta-blocker-use-during-pregnancy-in-the-growth-of-children-with-long-qt-syndrome
#17
Heta Huttunen, Matti Hero, Mitja Lääperi, Johanna Känsäkoski, Heikki Swan, Joel A Hirsch, Päivi J Miettinen, Taneli Raivio
Objective: Two missense mutations in KCNQ1 , an imprinted gene that encodes the alpha subunit of the voltage-gated potassium channel Kv7.1, cause autosomal dominant growth hormone deficiency and maternally inherited gingival fibromatosis. We evaluated endocrine features, birth size, and subsequent somatic growth of patients with long QT syndrome 1 (LQT1) due to loss-of-function mutations in KCNQ1 . Design: Medical records of 104 patients with LQT1 in a single tertiary care center between 1995 and 2015 were retrospectively reviewed...
2018: Frontiers in Endocrinology
https://www.readbyqxmd.com/read/29739726/new-onset-seizures-in-a-patient-with-long-qt-syndrome-lqts2-and-a-pathogenic-carboxyl-terminus-frameshift-variant-of-the-kcnh2-gene
#18
Katherine Zarroli, Henry Querfurth
In patients with Long QT Syndrome (LQTS), mutations in the potassium channel KCNH2 gene increase seizure susceptibility with missense mutations involving the pore region of the gene acting as a positive predictor of seizures. Seizures are less commonly reported in patients with carboxyl (C')-terminus mutations. This case report describes a young man who presented with syncope followed by a first seizure and was found to have LQTS caused by a pathogenic carboxyl-terminus deletion/frameshifting mutation of the KCNH2 gene...
May 5, 2018: Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia
https://www.readbyqxmd.com/read/29738690/recombinant-production-reconstruction-in-lipid-protein-nanodiscs-and-electron-microscopy-of-full-length-%C3%AE-subunit-of-human-potassium-channel-kv7-1
#19
Z O Shenkarev, M G Karlova, D S Kulbatskii, M P Kirpichnikov, E N Lyukmanova, O S Sokolova
Voltage-gated potassium channel Kv7.1 plays an important role in the excitability of cardiac muscle. The α-subunit of Kv7.1 (KCNQ1) is the main structural element of this channel. Tetramerization of KCNQ1 in the membrane results in formation of an ion channel, which comprises a pore and four voltage-sensing domains. Mutations in the human KCNQ1 gene are one of the major causes of inherited arrhythmias, long QT syndrome in particular. The construct encoding full-length human KCNQ1 protein was synthesized in this work, and an expression system in the Pichia pastoris yeast cells was developed...
May 2018: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/29738372/paradoxical-effects-of-sodium-calcium-exchanger-inhibition-on-torsade-de-pointes-and-early-afterdepolarization-in-a-heart-failure-rabbit-model
#20
Po-Cheng Chang, Yu-Ying Lu, Hui-Ling Lee, Shien-Fong Lin, Yen Chu, Ming-Shien Wen, Chung-Chuan Chou
Calcium homeostasis plays an important role in development of early afterdepolarizations (EADs) and torsade de pointes (TdP). The role of sodium-calcium exchanger (NCX) inhibition in genesis secondary Ca rise and EADs-TdP is still debated. Dual voltage and intracellular Ca optical mapping were conducted in 6 control and 9 failing rabbit hearts. After baseline electrophysiological and optical mapping studies, E4031 was given to simulate long QT syndrome. ORM-10103 was then administrated to examine the electrophysiological effects on EAD-TdP development...
May 3, 2018: Journal of Cardiovascular Pharmacology
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