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Long qt

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
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
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
Diana João Fonseca, Manuel Joaquim Vaz da Silva
INTRODUCTION AND OBJECTIVES: The importance of sodium channels for the normal electrical activity of the heart is emphasized by the fact that mutations (inherited or de novo) in genes that encode for these channels or their associated proteins cause arrhythmogenic syndromes such as the Brugada syndrome and the long QT syndrome (LQTS). The aim of this study is to conduct a review of the literature on the mutations in the sodium channel complex responsible for heart disease and the implications of a close relationship between genetics and the clinical aspects of the main cardiac channelopathies, namely at the level of diagnosis, risk stratification, prognosis, screening of family members and treatment...
March 7, 2018: Portuguese Journal of Cardiology: An Official Journal of the Portuguese Society of Cardiology
Timothy L Surman, Robert G Stuklis, Justin C Chan
BACKGROUND: Multiple case studies have suggested that video-assisted thoracoscopic sympathectomy (VATS) reduces the occurrence and frequency of symptoms in long QT syndrome (LQTS) [1,2,3]. To date there has not been a literature review to report on the short-term and long-term outcomes of this procedure. Our primary aims are to review the literature findings on the clinical outcomes of VATS sympathectomy for long QT and present a local centre case report on the outcomes of T2-T5 sympathectomy...
February 13, 2018: Heart, Lung & Circulation
Santiago Perez-Lloret, Olivier Rascol
L-DOPA induced dyskinesias (LIDs) may affect up to 40% of Parkinson's disease (PD) and impact negatively health-related quality of life. Amantadine has demonstrated significant antidyskinetic effects in animal PD models and in randomized double-blind placebo-controlled trials (RCTs) in patients with PD. These effects are thought to be related to the blockade of NMDA receptors modulating cortico-striatal glutamatergic-dopaminergic interactions involved in the genesis of LIDs. There are three pharmaceutical forms of amantadine currently available in the market: an oral immediate-release (IR) formulation, which is widely available; an extended-release (ER) formulation (ADS-5102) which has been recently developed and approved by the FDA; and an intravenous infusion (IV) solution, which is not commonly used in clinical practice...
March 7, 2018: Journal of Neural Transmission
Jesus Mates, Irene Mademont-Soler, Bernat Del Olmo, Carles Ferrer-Costa, Monica Coll, Alexandra Pérez-Serra, Ferran Picó, Catarina Allegue, Anna Fernandez-Falgueras, Patricia Álvarez, Raquel Yotti, Maria Angeles Espinosa, Georgia Sarquella-Brugada, Sergi Cesar, Ester Carro, Josep Brugada, Elena Arbelo, Pablo Garcia-Pavia, Mar Borregan, Eduardo Tizzano, Amador López-Granados, Francisco Mazuelos, Aranzazu Díaz de Bustamante, Maria Teresa Darnaude, José Ignacio González-Hevia, Felícitas Díaz-Flores, Francisco Trujillo, Anna Iglesias, Francisco Fernandez-Aviles, Oscar Campuzano, Ramon Brugada
Several studies have identified copy number variants (CNVs) as responsible for cardiac diseases associated with sudden cardiac death (SCD), but very few exhaustive analyses in large cohorts of patients have been performed, and they have been generally focused on a specific SCD-related disease. The aim of the present study was to screen for CNVs the most prevalent genes associated with SCD in a large cohort of patients who suffered sudden unexplained death or had an inherited cardiac disease (cardiomyopathy or channelopathy)...
March 6, 2018: European Journal of Human Genetics: EJHG
Valentina Kutyifa, Usama Daimee, Scott McNitt, Bronislava Polonsky, Charles Lowenstein, Kris Cutter, Coeli Lopes, Wojciech Zareba, Arthur J Moss
BACKGROUND: A comprehensive report on the clinical course of the three major genotypes of the long QT syndrome (LQTS) in a large U.S. patient cohort is lacking. METHODS: Our study consisted of 1,923 U.S. subjects from the Rochester-based LQTS Registry with genotype-positive LQT1 (n = 879), LQT2 (n = 807), and LQT3 (n = 237). We evaluated the risk of a first cardiac event (syncope, aborted cardiac arrest, or sudden cardiac death, whichever occurred first) from birth through age 50 years...
March 5, 2018: Annals of Noninvasive Electrocardiology
Andrew P Landstrom, Ernesto Fernandez, Jill A Rosenfeld, Yaping Yang, Andrew L Dailey-Schwartz, Christina Y Miyake, Hugh D Allen, Daniel J Penny, Jeffrey J Kim
BACKGROUND: Due to rapid expansion of clinical genetic testing, an increasing number of genetic variants of undetermined significance are being identified in children with unclear diagnostic value. Variants found in genes associated with heritable channelopathies, such as long QT syndrome (LQTS), are particularly difficult to interpret given the risk of sudden cardiac death associated with pathologic mutations. OBJECTIVE: To determine whether variants in LQTS-associated genes from whole exome sequencing (WES) represent disease-associated biomarkers or background genetic "noise...
March 1, 2018: Heart Rhythm: the Official Journal of the Heart Rhythm Society
Nam Nhut Phan, Kuan-Lun Li, Yen-Chang Lin
BACKGROUND: Arsenic has been shown to cause various diseases (such as blackfoot disease, cardiovascular diseases, bladder cancer and skin cancer) in many areas of the world. However, the effects of arsenic on cardiac rhythm functions still lack investigation. METHODS: In this study, different concentrations of arsenic were orally applied to Sprague Dawley rats in order to examine the relationship between arsenic and cardiovascular rhythm (i.e. long QT) via electrocardiography measurement...
March 2, 2018: Toxicology Mechanisms and Methods
C M Mak, S Pl Chen, N S Mok, W K Siu, H Hc Lee, C K Ching, P T Tsui, N C Fong, Y P Yuen, W T Poon, C Y Law, Y K Chong, Y W Chan, T C Yung, K Yy Fan, C W Lam
INTRODUCTION: Hereditary channelopathies and cardiomyopathies are potentially lethal and are clinically and genetically heterogeneous, involving at least 90 genes. Genetic testing can provide an accurate diagnosis, guide treatment, and enable cascade screening. The genetic basis among the Hong Kong Chinese population is largely unknown. We aimed to report on 28 unrelated patients with positive genetic findings detected from January 2006 to December 2015. METHODS: Sanger sequencing was performed for 28 unrelated patients with a clinical diagnosis of channelopathies or cardiomyopathies, testing for the following genes: KCNQ1, KCNH2, KCNE1, KCNE2, and SCN5A, for long QT syndrome; SCN5A for Brugada syndrome; RYR2 for catecholaminergic polymorphic ventricular tachycardia; MYH7 and MYBPC3 for hypertrophic cardiomyopathy; LMNA for dilated cardiomyopathy; and PKP2 and DSP for arrhythmogenic right ventricular dysplasia/cardiomyopathy...
March 2, 2018: Hong Kong Medical Journal, Xianggang Yi Xue za Zhi
Kathleen T Hickey, Amir Elzomor
The discovery of the human genome has ushered in a new era of molecular testing, advancing our knowledge and ability to identify cardiac channelopathies. Genetic variations can affect the opening and closing of the potassium, sodium, and calcium channels, resulting in arrhythmias and sudden death. Cardiac arrhythmias caused by disorders of ion channels are known as cardiac channelopathies. Nurses are important members of many interdisciplinary teams and must have a general understanding of the pathophysiology of the most commonly encountered cardiac channelopathies, electrocardiogram characteristics, approaches to treatment, and care for patients and their families...
2018: AACN Advanced Critical Care
Anna Garcia-Elias, Begoña Benito
Long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia are inherited primary electrical disorders that predispose to sudden cardiac death in the absence of structural heart disease. Also known as cardiac channelopathies, primary electrical disorders respond to mutations in genes encoding cardiac ion channels and/or their regulatory proteins, which result in modifications in the cardiac action potential or in the intracellular calcium handling that lead to electrical instability and life-threatening ventricular arrhythmias...
February 28, 2018: International Journal of Molecular Sciences
Mena Abdelsayed, Manpreet Ruprai, Peter C Ruben
E1784K is the most common mixed syndrome SCN5a mutation underpinning both Brugada syndrome type 1 (BrS1) and Long-QT syndrome type 3 (LQT3). The charge reversal mutant enhances the late sodium current (INa ) passed by the cardiac voltage-gated sodium channel (NaV 1.5), delaying cardiac repolarization. Exercise-induced triggers, like elevated temperature and cytosolic calcium, exacerbate E1784K late INa . In this study, we tested the effects of Ranolazine, the late INa blocker, on voltage-dependent and kinetic properties of E1784K at elevated temperature and cytosolic calcium...
February 26, 2018: Scientific Reports
Cecilia Villa Etchegoyen, Guillermo Alberto Keller, Sebastian Mrad, Sixuan Cheng, Guillermo DiGirolamo
Drug-induced QT interval prolongation is the most frequent cause of Long QT syndrome (LQTS) in the clinical practice. This electrophysiological entity, produced by an extended duration of the myocardial repolarization and reflected as a prolonged QT interval in the superficial electrocardiogram (EKG), increases the risk of polymorphic ventricular tachycardia (Torsades de Pointes) appearance and sudden death. Certain antiarrhythmic drugs such as amiodarone, sotalol, quinidine, procainamide, verapamil and diltiazem are known as drugs that, due to their mechanism of action, prolong the QT interval, demanding constant monitorization...
February 23, 2018: Current Clinical Pharmacology
Aurel T Tankeu, Marcel Azabji-Kenfack, Chris-Nadège Nganou, Eliane Ngassam, Liliane Kuate-Mfeukeu, Camille Mba, Mesmin Y Dehayem, Jean-Claude Mbanya, Eugene Sobngwi
OBJECTIVES: We aimed to determine the effect of propanolol on heart rate variability (HRV) in hyperthyroidism before antithyroid treatment. This was a before and after study, on ten patients presenting overt hyperthyroidism naïve to treatment. In each patient, a resting electrocardiogram was done followed by estimation of cardiac autonomic dysfunction during five maneuvers (Ewing battery tests). Long term HRV measurement was done using 24 h ambulatory electrocardiographic recording...
February 22, 2018: BMC Research Notes
Jussi T Koivumäki, Nikolay Naumenko, Tomi Tuomainen, Jouni Takalo, Minna Oksanen, Katja A Puttonen, Šárka Lehtonen, Johanna Kuusisto, Markku Laakso, Jari Koistinaho, Pasi Tavi
Background: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have emerged as a promising experimental tool for translational heart research and drug development. However, their usability as a human adult cardiomyocyte model is limited by their functional immaturity. Our aim is to analyse quantitatively those characteristics and how they differ from adult CMs. Methods and Results: We have developed a novel in silico model with all essential functional electrophysiology and calcium handling features of hiPSC-CMs...
2018: Frontiers in Physiology
Maria Ercu, Enno Klussmann
A-kinase anchoring proteins (AKAPs) and cyclic nucleotide phosphodiesterases (PDEs) are essential enzymes in the cyclic adenosine 3'-5' monophosphate (cAMP) signaling cascade. They establish local cAMP pools by controlling the intensity, duration and compartmentalization of cyclic nucleotide-dependent signaling. Various members of the AKAP and PDE families are expressed in the cardiovascular system and direct important processes maintaining homeostatic functioning of the heart and vasculature, e.g., the endothelial barrier function and excitation-contraction coupling...
February 20, 2018: Journal of Cardiovascular Development and Disease
Annelies Decloedt, Barbara Broux, Dominique De Clercq, Piet Deprez, Glenn Van Steenkiste, Lisse Vera, Sofie Ven, Gunther van Loon
BACKGROUND: Based on its pharmacokinetic profile and electrophysiological effects in healthy horses, sotalol potentially could be used as a long-term PO antiarrhythmic drug in horses. OBJECTIVES: To evaluate the effect of sotalol on heart rate (HR), QT interval, atrial fibrillatory rate, and success of cardioversion in horses with naturally occurring chronic atrial fibrillation (AF). ANIMALS: Twenty-eight horses referred for transvenous electrical cardioversion of AF were treated with 2 mg/kg sotalol PO q12h for 3 days before cardioversion, and 13 horses underwent the same protocol without sotalol administration...
February 20, 2018: Journal of Veterinary Internal Medicine
Atsuko Hirano, Tomohiko Takada, Mariko Senda, Hidemasa Takahashi, Takeo Suzuki
Background: Polymeraze I and transcript release factor ( PTRF ) mutations are a newly recognized disease, which cause congenital generalized lipodystrophy associated with myopathy. Case presentation: A 29-year-old man (height 126 cm; weight 22 kg) with a PTRF mutation was scheduled for mandibular dentigerous cystectomy. His primary symptoms were lipodystrophy, myopathy, long QT syndrome, refractory nephrosis, and abnormal lipid metabolism. Defibrillator pads were applied soon after the patient entered the operating room...
2018: JA Clin Rep
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